sdhci: tegra: Remove warnings about missing device-tree properties

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

It should be up to a board's device-tree writer to
properly describe all the necessary properties. Secondly, eventually all device-tree bindings will be converted to YAML, which allows to validate board DT files, giving a warning about missing properties. Hence let's remove the noisy warnings to stop the confusion.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/mmc/host/sdhci-tegra.c | 28 ++++------------------------
 1 file changed, 4 insertions(+), 24 deletions(-)

drivers/mmc/host/sdhci-tegra.c +4 -25

index 3e2c5101291d..83867629013d 100644
@@ -607,46 +607,26 @@ static void tegra_sdhci_parse_pad_autocal_dt(struct sdhci_host *host)
        err = device_property_read_u32(host->mmc->parent,
                        "nvidia,pad-autocal-pull-up-offset-3v3-timeout",
                        &autocal->pull_up_3v3_timeout);
-       if (err) {
-               if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
-                       (tegra_host->pinctrl_state_3v3_drv == NULL))
-                       pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
-                               mmc_hostname(host->mmc));
+       if (err)
                autocal->pull_up_3v3_timeout = 0;
-       }
 
        err = device_property_read_u32(host->mmc->parent,
                        "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
                        &autocal->pull_down_3v3_timeout);
-       if (err) {
-               if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
-                       (tegra_host->pinctrl_state_3v3_drv == NULL))
-                       pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
-                               mmc_hostname(host->mmc));
+       if (err)
                autocal->pull_down_3v3_timeout = 0;
-       }
 
        err = device_property_read_u32(host->mmc->parent,
                        "nvidia,pad-autocal-pull-up-offset-1v8-timeout",
                        &autocal->pull_up_1v8_timeout);
-       if (err) {
-               if (!IS_ERR(tegra_host->pinctrl_state_1v8) &&
-                       (tegra_host->pinctrl_state_1v8_drv == NULL))
-                       pr_warn("%s: Missing autocal timeout 1v8-pad drvs\n",
-                               mmc_hostname(host->mmc));
+       if (err)
                autocal->pull_up_1v8_timeout = 0;
-       }
 
        err = device_property_read_u32(host->mmc->parent,
                        "nvidia,pad-autocal-pull-down-offset-1v8-timeout",
                        &autocal->pull_down_1v8_timeout);
-       if (err) {
-               if (!IS_ERR(tegra_host->pinctrl_state_1v8) &&
-                       (tegra_host->pinctrl_state_1v8_drv == NULL))
-                       pr_warn("%s: Missing autocal timeout 1v8-pad drvs\n",
-                               mmc_hostname(host->mmc));
+       if (err)
                autocal->pull_down_1v8_timeout = 0;
-       }
 
        err = device_property_read_u32(host->mmc->parent,
                        "nvidia,pad-autocal-pull-up-offset-sdr104",
--

2.26.0

Quoted 4 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

Quoted 5 lines

It should be up to a board's device-tree writer to
properly describe all the necessary properties. Secondly, eventually all device-tree bindings will be converted to YAML, which allows to validate board DT files, giving a warning about missing properties. Hence let's remove the noisy warnings to stop the confusion.

Yep, makes sense. However, perhaps we should do this conversion then, rather than first drop the warnings?

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines · Dmitry Osipenko

Quoted 4 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Quoted 6 lines

Quoted 5 lines

It should be up to a board's device-tree writer to
properly describe all the necessary properties. Secondly, eventually all device-tree bindings will be converted to YAML, which allows to validate board DT files, giving a warning about missing properties. Hence let's remove the noisy warnings to stop the confusion.

Quoted 2 lines

Yep, makes sense. However, perhaps we should do this conversion then, rather than first drop the warnings?

I don't mind to postpone this patch. But again, IIUC, all these properties are optional, and thus, there is no critical need to verify them in DT right now, it could be done later on.

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines · Dmitry Osipenko

Quoted 4 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines · Dmitry Osipenko

Quoted 4 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 6 lines

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194 but not Tegra210 where these should also be necessary.

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps add a better way of identifying when they are necessary and when it is safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

	if (tegra_host->pinctrl_state_XYZ == NULL) {
		...
	}

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

So I think we either need to add those values where appropriate so that the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

19.05.2020 19:24, Thierry Reding пишет:

Quoted 30 lines · Dmitry Osipenko

Quoted 11 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 5 lines · Dmitry Osipenko

Quoted 3 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 6 lines

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194 but not Tegra210 where these should also be necessary.

Quoted 10 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps add a better way of identifying when they are necessary and when it is safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

	if (tegra_host->pinctrl_state_XYZ == NULL) {
		...
	}

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

Quoted 7 lines

So I think we either need to add those values where appropriate so that the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than clutter the driver, IMO.

Quoted 32 lines · Dmitry Osipenko

19.05.2020 19:24, Thierry Reding пишет:

Quoted 31 lines · Dmitry Osipenko

Quoted 12 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 5 lines · Dmitry Osipenko

Quoted 3 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 6 lines

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194 but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 10 lines

Quoted 10 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps add a better way of identifying when they are necessary and when it is safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

    if (tegra_host->pinctrl_state_XYZ == NULL) {
        ...
    }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

    err = device_property_read_u32(host->mmc->parent, "nvidia,pad-autocal-pull-down-offset-3v3-timeout", &autocal->pull_down_3v3_timeout);
    if (err) {
        if (!IS_ERR(tegra_host->pinctrl_state_3v3) && (tegra_host->pinctrl_state_3v3_drv == NULL)) pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n", mmc_hostname(host->mmc)); autocal->pull_down_3v3_timeout = 0;
    }

Quoted 10 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than clutter the driver, IMO.

Quoted 75 lines · Sowjanya Komatineni

Quoted 32 lines · Dmitry Osipenko

19.05.2020 19:24, Thierry Reding пишет:

Quoted 31 lines · Dmitry Osipenko

Quoted 12 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 5 lines · Dmitry Osipenko

Quoted 3 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 6 lines

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194 but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 10 lines

Quoted 10 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps add a better way of identifying when they are necessary and when it is safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

    if (tegra_host->pinctrl_state_XYZ == NULL) {
        ...
    }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

    err = device_property_read_u32(host->mmc->parent, "nvidia,pad-autocal-pull-down-offset-3v3-timeout", &autocal->pull_down_3v3_timeout);
    if (err) {
        if (!IS_ERR(tegra_host->pinctrl_state_3v3) && (tegra_host->pinctrl_state_3v3_drv == NULL)) pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n", mmc_hostname(host->mmc)); autocal->pull_down_3v3_timeout = 0;
    }

Quoted 10 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Quoted 101 lines · Sowjanya Komatineni

Quoted 75 lines · Sowjanya Komatineni

Quoted 32 lines · Dmitry Osipenko

19.05.2020 19:24, Thierry Reding пишет:

Quoted 31 lines · Dmitry Osipenko

Quoted 12 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 5 lines · Dmitry Osipenko

Quoted 3 lines

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 6 lines

Although, looking at the driver's code and TRM docs, it seems that all those properties are really irrelevant only to the older Terga20 SoC. So the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194 but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 10 lines

Quoted 10 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps add a better way of identifying when they are necessary and when it is safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

    if (tegra_host->pinctrl_state_XYZ == NULL) {
        ...
    }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

    err = device_property_read_u32(host->mmc->parent, "nvidia,pad-autocal-pull-down-offset-3v3-timeout", &autocal->pull_down_3v3_timeout);
    if (err) {
        if (!IS_ERR(tegra_host->pinctrl_state_3v3) && (tegra_host->pinctrl_state_3v3_drv == NULL)) pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n", mmc_hostname(host->mmc)); autocal->pull_down_3v3_timeout = 0;
    }

Quoted 10 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than clutter the driver, IMO.

Quoted 5 lines

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Quoted 146 lines · Sowjanya Komatineni

Quoted 135 lines · Sowjanya Komatineni

Quoted 98 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

    if (tegra_host->pinctrl_state_XYZ == NULL) {
        ...
    }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 26 lines

    err = device_property_read_u32(host->mmc->parent, "nvidia,pad-autocal-pull-down-offset-3v3-timeout", &autocal->pull_down_3v3_timeout);
    if (err) {
        if (!IS_ERR(tegra_host->pinctrl_state_3v3) && (tegra_host->pinctrl_state_3v3_drv == NULL)) pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n", mmc_hostname(host->mmc)); autocal->pull_down_3v3_timeout = 0;
    }

Quoted 12 lines

Quoted 8 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 4 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 167 lines · Sowjanya Komatineni

Quoted 146 lines · Sowjanya Komatineni

Quoted 135 lines · Sowjanya Komatineni

Quoted 98 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

    if (tegra_host->pinctrl_state_XYZ == NULL) {
        ...
    }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 26 lines

    err = device_property_read_u32(host->mmc->parent,
            "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
            &autocal->pull_down_3v3_timeout);
    if (err) {
        if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
            (tegra_host->pinctrl_state_3v3_drv == NULL))
            pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                mmc_hostname(host->mmc));
        autocal->pull_down_3v3_timeout = 0;
    }

Quoted 12 lines

Quoted 8 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 4 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Quoted 7 lines

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 165 lines · Dmitry Osipenko

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 164 lines · Sowjanya Komatineni

Quoted 138 lines · Sowjanya Komatineni

Quoted 129 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

     if (tegra_host->pinctrl_state_XYZ == NULL) {
         ...
     }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

     err = device_property_read_u32(host->mmc->parent,
             "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
             &autocal->pull_down_3v3_timeout);
     if (err) {
         if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
             (tegra_host->pinctrl_state_3v3_drv == NULL))
             pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                 mmc_hostname(host->mmc));
         autocal->pull_down_3v3_timeout = 0;
     }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 166 lines · Ulf Hansson

Quoted 165 lines · Dmitry Osipenko

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 164 lines · Sowjanya Komatineni

Quoted 138 lines · Sowjanya Komatineni

Quoted 129 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and I had to tell to ignore them because these warning are irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

     if (tegra_host->pinctrl_state_XYZ == NULL) {
         ...
     }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

     err = device_property_read_u32(host->mmc->parent,
             "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
             &autocal->pull_down_3v3_timeout);
     if (err) {
         if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
             (tegra_host->pinctrl_state_3v3_drv == NULL))
             pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                 mmc_hostname(host->mmc));
         autocal->pull_down_3v3_timeout = 0;
     }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Quoted 197 lines · Ulf Hansson

Quoted 166 lines · Dmitry Osipenko

Quoted 165 lines

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 164 lines · Sowjanya Komatineni

Quoted 138 lines · Sowjanya Komatineni

Quoted 129 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

     if (tegra_host->pinctrl_state_XYZ == NULL) {
         ...
     }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

     err = device_property_read_u32(host->mmc->parent,
             "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
             &autocal->pull_down_3v3_timeout);
     if (err) {
         if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
             (tegra_host->pinctrl_state_3v3_drv == NULL))
             pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                 mmc_hostname(host->mmc));
         autocal->pull_down_3v3_timeout = 0;
     }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?

22.05.2020 15:13, Thierry Reding пишет:

Quoted 212 lines · Sowjanya Komatineni

Quoted 197 lines · Ulf Hansson

Quoted 166 lines · Dmitry Osipenko

Quoted 165 lines

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 164 lines · Sowjanya Komatineni

Quoted 138 lines · Sowjanya Komatineni

Quoted 129 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

On Sat, 16 May 2020 at 17:44, Dmitry Osipenko <[email protected]>
wrote:
Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.
Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

     if (tegra_host->pinctrl_state_XYZ == NULL) {
         ...
     }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

     err = device_property_read_u32(host->mmc->parent,
             "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
             &autocal->pull_down_3v3_timeout);
     if (err) {
         if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
             (tegra_host->pinctrl_state_3v3_drv == NULL))
             pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                 mmc_hostname(host->mmc));
         autocal->pull_down_3v3_timeout = 0;
     }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

Quoted 3 lines

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?

I don't see the warnings on T30 using Sowjanya's patch which checks for NVQUIRK_NEEDS_PAD_CONTROL and not NVQUIRK_HAS_PADCALIB.

Quoted 208 lines · Dmitry Osipenko

22.05.2020 15:13, Thierry Reding пишет:

Quoted 207 lines · Sowjanya Komatineni

Quoted 193 lines · Ulf Hansson

Quoted 165 lines · Dmitry Osipenko

Quoted 164 lines

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 163 lines · Sowjanya Komatineni

Quoted 137 lines · Sowjanya Komatineni

Quoted 128 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 22 lines

19.05.2020 10:28, Ulf Hansson пишет:
On Sat, 16 May 2020 at 17:44, Dmitry Osipenko <[email protected]>
wrote:
Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.
Why are the warnings irrelevant?
That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Although, looking at the driver's code and TRM docs, it seems
that all
those properties are really irrelevant only to the older Terga20
SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are
optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

      if (tegra_host->pinctrl_state_XYZ == NULL) {
          ...
      }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 23 lines

      err = device_property_read_u32(host->mmc->parent,
              "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
              &autocal->pull_down_3v3_timeout);
      if (err) {
          if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
              (tegra_host->pinctrl_state_3v3_drv == NULL))
              pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                  mmc_hostname(host->mmc));
          autocal->pull_down_3v3_timeout = 0;
      }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

Quoted 5 lines

Quoted 3 lines

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?

I don't see the warnings on T30 using Sowjanya's patch which checks for NVQUIRK_NEEDS_PAD_CONTROL and not NVQUIRK_HAS_PADCALIB.

Yeah, I noticed that too when looking at Sowjanya's patch. The fact that we have two of these quirks is somewhat confusing to me. Perhaps we can add a comment near their definition to clarify what their purpose is?

Thierry

Quoted 209 lines · Thierry Reding

Quoted 208 lines · Dmitry Osipenko

22.05.2020 15:13, Thierry Reding пишет:

Quoted 207 lines · Sowjanya Komatineni

Quoted 193 lines · Ulf Hansson

Quoted 165 lines · Dmitry Osipenko

Quoted 164 lines

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 163 lines · Sowjanya Komatineni

Quoted 137 lines · Sowjanya Komatineni

Quoted 128 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

19.05.2020 10:28, Ulf Hansson пишет:
On Sat, 16 May 2020 at 17:44, Dmitry Osipenko <[email protected]>
wrote:
Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.
Why are the warnings irrelevant?
That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Although, looking at the driver's code and TRM docs, it seems
that all
those properties are really irrelevant only to the older Terga20
SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are
optional, which is correct.
Optional only means that drivers must not fail if these properties
aren't found, it doesn't mean that the driver can't warn that they
are missing.

Quite possibly the only reason why they were made optional is because
they weren't part of the bindings since the beginning. Anything added
to a binding after the first public release has to be optional by
definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that
there are only values for these in device tree for Tegra186 and
Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the
warnings were added. If these values /should/ be there on a subset of
Tegra, then I think we should keep them, or add them again, but
perhaps
add a better way of identifying when they are necessary and when
it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just
wrong. Or at the very least they seem redundant. It looks to me like
they can just be:

Quoted 7 lines

Quoted 7 lines

if (tegra_host->pinctrl_state_XYZ == NULL) {
...
}

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's
also obvious why we're warning about them on platforms where these
properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 23 lines

      err = device_property_read_u32(host->mmc->parent,
              "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
              &autocal->pull_down_3v3_timeout);
      if (err) {
          if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
              (tegra_host->pinctrl_state_3v3_drv == NULL))
              pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                  mmc_hostname(host->mmc));
          autocal->pull_down_3v3_timeout = 0;
      }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so
that
the warning doesn't show, or we need to narrow down where they are
really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only
needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

Quoted 5 lines

Quoted 5 lines

Quoted 3 lines

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?

I don't see the warnings on T30 using Sowjanya's patch which checks for NVQUIRK_NEEDS_PAD_CONTROL and not NVQUIRK_HAS_PADCALIB.

Both of these quirks are different.

PADCALIB is for auto calibration support.

NEEDS_PAD_CONTROL is for SoC having separate 3V3 and 1V8 pads where they have pad state selection and also diff drive strengths apply based on 3V3 and 1V8 which are used only when auto cal is not used/failed.

Quoted 218 lines · Sowjanya Komatineni

Quoted 208 lines · Thierry Reding

Quoted 207 lines · Dmitry Osipenko

22.05.2020 15:13, Thierry Reding пишет:

Quoted 206 lines · Sowjanya Komatineni

Quoted 192 lines · Ulf Hansson

Quoted 164 lines · Dmitry Osipenko

Quoted 163 lines

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 162 lines · Sowjanya Komatineni

Quoted 136 lines · Sowjanya Komatineni

Quoted 127 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:
On Tue, May 19, 2020 at 05:05:27PM +0300, Dmitry Osipenko wrote:
19.05.2020 10:28, Ulf Hansson пишет:
On Sat, 16 May 2020 at 17:44, Dmitry Osipenko <[email protected]>
wrote:
Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.
Why are the warnings irrelevant?
That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Although, looking at the driver's code and TRM docs, it seems
that all
those properties are really irrelevant only to the older Terga20
SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are
optional, which is correct.
Optional only means that drivers must not fail if these properties
aren't found, it doesn't mean that the driver can't warn that they
are missing.

Quite possibly the only reason why they were made optional is because
they weren't part of the bindings since the beginning. Anything added
to a binding after the first public release has to be optional by
definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that
there are only values for these in device tree for Tegra186 and
Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 19 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the
warnings were added. If these values /should/ be there on a subset of
Tegra, then I think we should keep them, or add them again, but
perhaps
add a better way of identifying when they are necessary and when
it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just
wrong. Or at the very least they seem redundant. It looks to me like
they can just be:

if (tegra_host->pinctrl_state_XYZ == NULL) {
...
}

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's
also obvious why we're warning about them on platforms where these
properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 22 lines

       err = device_property_read_u32(host->mmc->parent,
               "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
               &autocal->pull_down_3v3_timeout);
       if (err) {
           if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
               (tegra_host->pinctrl_state_3v3_drv == NULL))
               pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                   mmc_hostname(host->mmc));
           autocal->pull_down_3v3_timeout = 0;
       }

Quoted 11 lines

So I think we either need to add those values where appropriate so
that
the warning doesn't show, or we need to narrow down where they are
really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only
needed on Tegra210 and later or if these also apply to older chips.
Either way will be cleaner to convert the DT binding to YAML rather
than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So,  these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

Quoted 5 lines

Quoted 5 lines

Quoted 3 lines

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?

I don't see the warnings on T30 using Sowjanya's patch which checks for NVQUIRK_NEEDS_PAD_CONTROL and not NVQUIRK_HAS_PADCALIB.

Both of these quirks are different.

PADCALIB is for auto calibration support.

Quoted 3 lines

NEEDS_PAD_CONTROL is for SoC having separate 3V3 and 1V8 pads where they have pad state selection and also diff drive strengths apply based on 3V3 and 1V8 which are used only when auto cal is not used/failed.

Great, would you mind sending out a patch that describes their uses somewhere above their definitions? It'd be good to have this documented in the code in case this ever comes up again.

Thierry

Quoted 197 lines · Sowjanya Komatineni

Quoted 166 lines · Ulf Hansson

Quoted 165 lines · Dmitry Osipenko

19.05.2020 23:44, Sowjanya Komatineni пишет:

Quoted 164 lines · Sowjanya Komatineni

Quoted 138 lines · Sowjanya Komatineni

Quoted 129 lines · Sowjanya Komatineni

Quoted 95 lines · Dmitry Osipenko

Quoted 37 lines

19.05.2020 19:24, Thierry Reding пишет:

Quoted 36 lines · Dmitry Osipenko

Quoted 14 lines

19.05.2020 10:28, Ulf Hansson пишет:

Quoted 7 lines

Quoted 4 lines · Dmitry Osipenko

Several people asked me about the MMC warnings in the KMSG log and
I had to tell to ignore them because these warning are
irrelevant to
pre-Tegra210 SoCs.

Why are the warnings irrelevant?

That's what the DT binding doc says [1].

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt

Quoted 8 lines

Although, looking at the driver's code and TRM docs, it seems that all
those properties are really irrelevant only to the older Terga20 SoC. So
the binding doc is a bit misleading.

Nevertheless, the binding explicitly says that the properties are optional, which is correct.

Optional only means that drivers must not fail if these properties aren't found, it doesn't mean that the driver can't warn that they are missing.

Quite possibly the only reason why they were made optional is because they weren't part of the bindings since the beginning. Anything added to a binding after the first public release has to be optional by definition, otherwise DT ABI wouldn't be stable.

I think these warnings were added on purpose, though I also see that there are only values for these in device tree for Tegra186 and Tegra194
but not Tegra210 where these should also be necessary.

dt binding doc we have is common for MMC, SD and SDIO of all Tegras. Its not mandatory to have both 3v3 and 1v8 in device tree as based on signal mode.

As these driver strengths are SoC specific, they are part of Tegra SoC specific device tree where same values will be applicable to all Tegra SoC specific platforms.

Based on interface usage on platform, we use one or both of them like sdcard supports dual voltage and we use both 3V3 and 1V8 but if same interface is used for WIFI SD we use 1V8 only.

So made these dt properties as optional.

Other reason they are optional is, Tegra210 and prior has drive strength settings part of apb_misc and Tegra186 and later has driver strengths part of SDMMC controller. So,

- Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths are applicable for Tegra210 and prior.
- dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are for T186 onwards for driver strengths

Looks like dt binding doc need fix to clearly document these based on SoC or agree with Yaml we can conditionally specify pinctrl or dt properties based on SoC dependent.

Quoted 12 lines

Quoted 12 lines

Adding Sowjanya who wrote this code. Perhaps she can clarify why the warnings were added. If these values /should/ be there on a subset of Tegra, then I think we should keep them, or add them again, but perhaps
add a better way of identifying when they are necessary and when it is
safe to work without them.

That said, looking at those checks I wonder if they are perhaps just wrong. Or at the very least they seem redundant. It looks to me like they can just be:

Quoted 7 lines

Quoted 7 lines

     if (tegra_host->pinctrl_state_XYZ == NULL) {
         ...
     }

That !IS_ERR(...) doesn't seem to do anything. But in that case, it's also obvious why we're warning about them on platforms where these properties don't exist in DT.

As drive strengths are through dt properties for T186 and later and thru pinctrl for T210 and prior, driver first checks for dt autocal timeout pull-up/down properties and if they are not found, it then checks for presence of pinctrl_state_xyx_drv only when valid pinctrl_state_xyz is present.

Driver expects either pinctrl or dt properties and shows warning when neither of them are present as its mandatory to use fixed driver strengths when auto calibration fails.

Quoted 24 lines

     err = device_property_read_u32(host->mmc->parent,
             "nvidia,pad-autocal-pull-down-offset-3v3-timeout",
             &autocal->pull_down_3v3_timeout);
     if (err) {
         if (!IS_ERR(tegra_host->pinctrl_state_3v3) &&
             (tegra_host->pinctrl_state_3v3_drv == NULL))
             pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n",
                 mmc_hostname(host->mmc));
         autocal->pull_down_3v3_timeout = 0;
     }

Quoted 11 lines

Quoted 7 lines

So I think we either need to add those values where appropriate so that
the warning doesn't show, or we need to narrow down where they are really needed and add a corresponding condition.

But again, perhaps Sowjanya can help clarify if these really are only needed on Tegra210 and later or if these also apply to older chips.

Either way will be cleaner to convert the DT binding to YAML rather than
clutter the driver, IMO.

Auto calibration is present from Tegra30 onward and looking into change where autocalibration was added to sdhci driver somehow it was enabled only for T30/T210/T186/T194.

tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration was added to driver and I see this dt parse is being done irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms without auto cal enabled in driver, these messages shows up.

Quoted 4 lines

This should be fixed in driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set to avoid dt parsing to happen on platforms that don't have auto cal enabled.

Warning on missing drive strengths when auto cal is enabled should be present as we should switch to fixed recommended drive strengths when auto cal fails.

Quoted 7 lines

So probably proper fix should be

- allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set

- current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree.

[Correction] T30 has same drive strengths to use irrespective of signal voltage and it doesn't have pad control. So for T3- we can update device tree to specify "default" pinctrl with drvup/dn settings.

Quoted 3 lines

- Keep warning message of missing auto cal timeouts as its mandatory to use fixed recommended driver strengths when auto cal fails.

Regarding warnings, I guess simpler and easy fix is to remove warning message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were already added for T210/186/194 where we need and old device tree don't have them but the case where auto cal can fail is very rare.

Otherwise should update driver to allow tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set and also within tegra_sdhci_parse_pad_autocal_dt() show warning of missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set.

Thierry, please suggest if you prefer to removing warnings or fix driver to show warning based on PADCALIB and PAD_CONTROL quirks.

Quoted 7 lines

Quoted 7 lines

The SDIO PINCTRL drive-strengths are usually a part of the board's default PINCTRL state, which is either preset by bootloader or by PINCTRL driver early at a boot time.

The SDIO drive-strengths values should be board-specific and not SoC-specific because they should depend on the electrical properties of the board, IIUC.

Drive strengths we program here when auto calibration fails are recommended values based on pre-SI circuit analysis and characterized across PVT.

So, these fail safe values are same for all boards of specific SoC as all platform designs follow the design guidelines.

Quoted 6 lines

Quoted 6 lines

If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the device-trees, then the DT binding is wrong since it says that all properties are optional. But I think that the current binding is okay, since today SDHCI PINCTRL drive-strengths are specified implicitly in the device-trees, and thus, there is no real need to emit the noisy warnings in this case.

Quoted 8 lines

For now I will keep $subject patch applied, but please tell me if I should drop it so we can start over.

In any case, I would appreciate it if someone could have a stab at converting sdhci and tegra DT bindings to yaml.

Kind regards
Uffe

Quoted 8 lines

HI Uffe,

Please drop $subject patch. Will send patch that allows parsing for these properties only for SoC where auto cal is enabled as that's where driver needs these properties.

So with this fix, warning will not show up on systems where autocal is not enabled.

Yes, I think that's a better option. Have we ensured that on all systems where autocal is enabled these values are part of the device tree? Just making sure that we're not going to have some generation still spit out these warnings because we forgot to update the device tree.

For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a patch that also adds the properties for Tegra30?