mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock

On Armada 7K/8K we need to explicitly enable the bus clock. The bus clock is optional because not all the SoCs need them but at least for Armada 7K/8K it is actually mandatory.

The binding documentation is updating accordingly.

Without this patch the kernel hand during boot if the mvpp2.2 network driver was not present in the kernel. Indeed the clock needed by the xenon controller was set by the network driver.

Fixes 3a3748dba881 ("mmc: sdhci-xenon: Add Marvell Xenon SDHC core

functionality)"

CC Stable <[email protected]>

Signed-off-by Gregory CLEMENT <[email protected]>

---
Hi Ulf and Adrian,

This patch should be merged in 4.14-rc, as it fixes real issues.

This patch maye looks like just as a nice clean-up but it is not. On the earlier version of the series adding the support for the xenon controller there was already this axi bus clock. But at this moment the documentation for the clock on the Armada 7K/8K was missing and there was no driver for it, so we just use the clock set by the bootloader and never change them that's why it worked without any visible problem.

Then as explained in the commit log the network driver enabled the clock for us, and it happened that it was setup before the xenon driver. It is only thanks the new information we received on the clocks of the Sov and with more exhaustive testes that we found this issue and the fix for it.

Thanks,

Gregory

Changelog:
v1->v2:
- manage the -EPROBE_DEFER case
- remove warning message when axi clock is not present
- remove useless test before clk_disable_unprepare()

 .../bindings/mmc/marvell,xenon-sdhci.txt           | 12 ++++++-----
 drivers/mmc/host/sdhci-xenon.c                     | 25 ++++++++++++++++++----
 drivers/mmc/host/sdhci-xenon.h                     |  1 +
 3 files changed, 29 insertions(+), 9 deletions(-)

Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt +7 -5

index b878a1e305af..ed1456f5c94d 100644
@@ -16,11 +16,13 @@ Required Properties:
 
 - clocks:
   Array of clocks required for SDHC.
-  Require at least input clock for Xenon IP core.
+  Require at least input clock for Xenon IP core. For Armada AP806 and
+  CP110, the AXI clock is also mandatory.
 
 - clock-names:
   Array of names corresponding to clocks property.
   The input clock for Xenon IP core should be named as "core".
+  The input clock for the AXI bus must be named as "axi".
 
 - reg:
   * For "marvell,armada-3700-sdhci", two register areas.

@@ -106,8 +108,8 @@ Example:
                compatible = "marvell,armada-ap806-sdhci";
                reg = <0xaa0000 0x1000>;
                interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>
-               clocks = <&emmc_clk>;
-               clock-names = "core";
+               clocks = <&emmc_clk>, <&axi_clk>;
+               clock-names = "core", "axi";
                bus-width = <4>;
                marvell,xenon-phy-slow-mode;
                marvell,xenon-tun-count = <11>;

@@ -126,8 +128,8 @@ Example:
                interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>
                vqmmc-supply = <&sd_vqmmc_regulator>;
                vmmc-supply = <&sd_vmmc_regulator>;
-               clocks = <&sdclk>;
-               clock-names = "core";
+               clocks = <&sdclk>, <&axi_clk>;
+               clock-names = "core", "axi";
                bus-width = <4>;
                marvell,xenon-tun-count = <9>;
        };

drivers/mmc/host/sdhci-xenon.c +21 -4

index 2eec2e652c53..15f912d08a4c 100644
@@ -466,6 +466,7 @@ static int xenon_probe(struct platform_device *pdev)
 {
        struct sdhci_pltfm_host *pltfm_host;
        struct sdhci_host *host;
+       struct xenon_priv *priv;
        int err;
 
        host = sdhci_pltfm_init(pdev, &sdhci_xenon_pdata,

@@ -474,6 +475,7 @@ static int xenon_probe(struct platform_device *pdev)
                return PTR_ERR(host);
 
        pltfm_host = sdhci_priv(host);
+       priv = sdhci_pltfm_priv(pltfm_host);
 
        /*
         * Link Xenon specific mmc_host_ops function,

@@ -491,9 +493,21 @@ static int xenon_probe(struct platform_device *pdev)
        if (err)
                goto free_pltfm;
 
+       priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
+       if (IS_ERR(priv->axi_clk)) {
+               err = PTR_ERR(priv->axi_clk);
+               if (err == -EPROBE_DEFER)
+                       goto err_clk;
+               priv->axi_clk = NULL;
+       } else {
+               err = clk_prepare_enable(priv->axi_clk);
+               if (err)
+                       goto err_clk;
+       }
+
        err = mmc_of_parse(host->mmc);
        if (err)
-               goto err_clk;
+               goto err_clk_axi;
 
        sdhci_get_of_property(pdev);
 

@@ -502,11 +516,11 @@ static int xenon_probe(struct platform_device *pdev)
        /* Xenon specific dt parse */
        err = xenon_probe_dt(pdev);
        if (err)
-               goto err_clk;
+               goto err_clk_axi;
 
        err = xenon_sdhc_prepare(host);
        if (err)
-               goto err_clk;
+               goto err_clk_axi;
 
        pm_runtime_get_noresume(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);

@@ -527,6 +541,8 @@ static int xenon_probe(struct platform_device *pdev)
        pm_runtime_disable(&pdev->dev);
        pm_runtime_put_noidle(&pdev->dev);
        xenon_sdhc_unprepare(host);
+err_clk_axi:
+       clk_disable_unprepare(priv->axi_clk);
 err_clk:
        clk_disable_unprepare(pltfm_host->clk);
 free_pltfm:

@@ -538,6 +554,7 @@ static int xenon_remove(struct platform_device *pdev)
 {
        struct sdhci_host *host = platform_get_drvdata(pdev);
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+       struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
 
        pm_runtime_get_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

@@ -546,7 +563,7 @@ static int xenon_remove(struct platform_device *pdev)
        sdhci_remove_host(host, 0);
 
        xenon_sdhc_unprepare(host);
-
+       clk_disable_unprepare(priv->axi_clk);
        clk_disable_unprepare(pltfm_host->clk);
 
        sdhci_pltfm_free(pdev);

drivers/mmc/host/sdhci-xenon.h +1 -1

index 2bc0510c0769..9994995c7c56 100644
@@ -83,6 +83,7 @@ struct xenon_priv {
        unsigned char   bus_width;
        unsigned char   timing;
        unsigned int    clock;
+       struct clk      *axi_clk;
 
        int             phy_type;
        /*
--

2.14.1

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Hi Gregory,
I tested this v2 patch on my armada3700 board.

Tested-by Zhoujie Wu <[email protected]>

On Armada 7K/8K we need to explicitly enable the bus clock. The bus clock is optional because not all the SoCs need them but at least for Armada 7K/8K it is actually mandatory.

The binding documentation is updating accordingly.

Without this patch the kernel hand during boot if the mvpp2.2 network driver was not present in the kernel. Indeed the clock needed by the xenon controller was set by the network driver.

Fixes 3a3748dba881 ("mmc: sdhci-xenon: Add Marvell Xenon SDHC core

functionality)"

CC Stable <[email protected]>

Signed-off-by Gregory CLEMENT <[email protected]>

drivers/mmc/host/sdhci-xenon.c +2 -0

index 2eec2e652c53..15f912d08a4c 100644
@@ -466,6 +466,7 @@ static int xenon_probe(struct platform_device *pdev)
 {
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_host *host;
+	struct xenon_priv *priv;
 	int err;
 
 	host = sdhci_pltfm_init(pdev, &sdhci_xenon_pdata,

@@ -474,6 +475,7 @@ static int xenon_probe(struct platform_device *pdev)
 		return PTR_ERR(host);
 
 	pltfm_host = sdhci_priv(host);
+	priv = sdhci_pltfm_priv(pltfm_host);
 
 	/*
 	 * Link Xenon specific mmc_host_ops function,

drivers/mmc/host/sdhci-xenon.c static int xenon_probe(struct platform_device *pdev) · line 501

Quoted 6 lines

drivers/mmc/host/sdhci-xenon.c +6 -0

+	priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
+	if (IS_ERR(priv->axi_clk)) {
+		err = PTR_ERR(priv->axi_clk);
+		if (err == -EPROBE_DEFER)
+			goto err_clk;
+		priv->axi_clk = NULL;  

IMHO, this assignment could be removed. What do you think?

Hello,

Quoted 8 lines · Jisheng Zhang

drivers/mmc/host/sdhci-xenon.c static int xenon_probe(struct platform_device *pdev) · line 501

Quoted 6 lines

drivers/mmc/host/sdhci-xenon.c +6 -0

+	priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
+	if (IS_ERR(priv->axi_clk)) {
+		err = PTR_ERR(priv->axi_clk);
+		if (err == -EPROBE_DEFER)
+			goto err_clk;
+		priv->axi_clk = NULL;    

IMHO, this assignment could be removed. What do you think?

No, because if the clock is not present in the Device Tree, priv->axi_clk will contain an error code encoded as a pointer, so priv->axi_clk will not be NULL. Hence the rest of the code that will

operate on this clock will believe there is a valid clock pointed by priv->axi_clk. So we really want to reset it to NULL when there was an error getting the clock.

Best regards,

Thomas

Hi Thomas,

Quoted 13 lines · On Sat, 30 Sep 2017 08:07:10 +0200 Thomas Petazzoni wrote:

Hello,

Quoted 8 lines · Jisheng Zhang

drivers/mmc/host/sdhci-xenon.c static int xenon_probe(struct platform_device *pdev) · line 501

Quoted 6 lines

drivers/mmc/host/sdhci-xenon.c +6 -0

+	priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
+	if (IS_ERR(priv->axi_clk)) {
+		err = PTR_ERR(priv->axi_clk);
+		if (err == -EPROBE_DEFER)
+			goto err_clk;
+		priv->axi_clk = NULL;    

IMHO, this assignment could be removed. What do you think?

Quoted 3 lines

No, because if the clock is not present in the Device Tree, priv->axi_clk will contain an error code encoded as a pointer, so priv->axi_clk will not be NULL. Hence the rest of the code that will

FWICT, the clk_disable_unprepare() could also check whether the clk is err, am I wrong?

Quoted 8 lines

operate on this clock will believe there is a valid clock pointed by priv->axi_clk. So we really want to reset it to NULL when there was an error getting the clock.

Best regards,

Thomas