Add AM437x RTC

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 10 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

Quoted 2 lines

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

So maybe the comments in the $subject patch are incorrect for that?

What we really should have is also status = "incomplete" where the dev entry gets created, but the driver never probes. This would be for devices that are still there within the SoC, but not pinned out for the board in question.

We still may need also ti,no-init too for devices that we don't want hwmod to do anything with, for example in secure mode if some blocks are not available to Linux at all. I believe that's what's going on with n900 crypto accelerators for example.

Regards,

Tony

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Or am I missing something here?

Regards,

Tony

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

Quoted 43 lines · Dave Gerlach

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 7 lines

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

Oh OK, I think you're right. I was thinking of omap_device_build_from_dt(), sorry. Looks like the hwmod IO address data does get populated even for status = "disabled" although the dev entry won't get created and omap_device_build_from_dt() never gets called.

Quoted 9 lines

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

OK sounds like some dts property is needed to signal this.

Quoted 5 lines

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Quoted 2 lines

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

OK thanks for explaining it. I'm fine with this patch, Paul may have other issues. The other option would be to use status = "disabled" to not touch the device at all like Paul suggested. I wonder if that's going to break PM on some devices though..

Regards,

Tony

Quoted 43 lines · Dave Gerlach

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 7 lines

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

Oh OK, I think you're right. I was thinking of omap_device_build_from_dt(), sorry. Looks like the hwmod IO address data does get populated even for status = "disabled" although the dev entry won't get created and omap_device_build_from_dt() never gets called.

Quoted 9 lines

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

OK sounds like some dts property is needed to signal this.

Quoted 6 lines

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Quoted 2 lines

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

OK thanks for explaining it. I'm fine with this patch, Paul may have other issues. The other option would be to use status = "disabled" to not touch the device at all like Paul suggested. I wonder if that's going to break PM on some devices though..

Hi Dave,

Quoted 67 lines · Tony Lindgren

Quoted 43 lines · Dave Gerlach

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 7 lines

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

Oh OK, I think you're right. I was thinking of omap_device_build_from_dt(), sorry. Looks like the hwmod IO address data does get populated even for status = "disabled" although the dev entry won't get created and omap_device_build_from_dt() never gets called.

Quoted 9 lines

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

Quoted 1 line

OK sounds like some dts property is needed to signal this.

As I understand, there is device "RTC" and this device has status 'disabled', so there is reasonable question why do we need to touch it at all? The HWMOD is some kind of SoC description, which was needed before DT. Now with DT in place it seems unreasonable to touch any IP block which:
- are not defined in DT
- has status 'disabled'.
in above cases the u-boot has to dial with IP block if it's invisible for Kernel.

The HWMOD framework intended to reset and put in some predefined states IPs which are visible for the Kernel, so then proper driver can start working with IP or IP will be kept in some low-power state if there is no driver.

Such kind of changes really confused :(, because when I'm looking on DT and see - status='disabled' I suppose that such IP will not be touched by Kernel. But it's NOT really 'disabled'. It's kinda 'partially disabled' or 'not present' or 'unused' ..
(if someone will decide to continue with such approach - it could be more
useful to define new value for 'status' parameter :P).
Also, just imaging that OMAP kernel is used with Xen as DomU and how hard will
it be to find and cut off all such tricks :(

Did I miss something?

Quoted 6 lines

Quoted 6 lines

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Quoted 8 lines

Quoted 2 lines

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

OK thanks for explaining it. I'm fine with this patch, Paul may have other issues. The other option would be to use status = "disabled" to not touch the device at all like Paul suggested. I wonder if that's going to break PM on some devices though..

Regards,
-grygorii

Quoted 45 lines · Grygorii Strashko

Quoted 44 lines · Tony Lindgren

Quoted 43 lines · Dave Gerlach

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 7 lines

Quoted 7 lines

Quoted 7 lines

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

Quoted 10 lines

Quoted 10 lines

Oh OK, I think you're right. I was thinking of omap_device_build_from_dt(), sorry. Looks like the hwmod IO address data does get populated even for status = "disabled" although the dev entry won't get created and omap_device_build_from_dt() never gets called.

Quoted 4 lines

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can

Quoted 7 lines

Quoted 7 lines

Quoted 5 lines

take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

OK sounds like some dts property is needed to signal this.

Quoted 9 lines

As I understand, there is device "RTC" and this device has status 'disabled', so there is reasonable question why do we need to touch it at all? The HWMOD is some kind of SoC description, which was needed before DT. Now with DT in place it seems unreasonable to touch any IP block which:
- are not defined in DT
- has status 'disabled'.
in above cases the u-boot has to dial with IP block if it's invisible for Kernel.

Quoted 3 lines

The HWMOD framework intended to reset and put in some predefined states IPs which are visible for the Kernel, so then proper driver can start working with IP or IP will be kept in some low-power state if there is no driver.

Currently we still need this hwmod behavior as not all IPs are in an ideal state for PM by default. Not sure if you saw my last email in this thread but I gave an example for USB hwmod:

If no USB driver is bound even just letting omap_device idle it using the USB_ CLKCTRL in the PRCM will not work properly, because the USB on am33xx expects it's SYSCONFIG STANDBY_MODE to be software supervised, the default state (SMART_STANDBY) does not let the IP go into standby so the IP gets stuck in a partially off state but does not actually shut down as expected.

So we need to be able to touch the dt nodes even if they are marked as disabled because we need to get the IO address to have access to the SYSCONFIG register. I am not trying to introduce any major new changes to omap_hwmod layer, I am just trying to allow it to work in more situations.

This flag would only exist to PREVENT any hwmod action from happening in certain cases where we cannot even touch the IP for whatever reason (in the first case that this patch intends to be used for, the RTC IP on am43x-epos-evm which is disabled by the board configuration).

Quoted 24 lines

Such kind of changes really confused :(, because when I'm looking on DT and see - status='disabled' I suppose that such IP will not be touched by Kernel. But it's NOT really 'disabled'. It's kinda 'partially disabled' or 'not present' or 'unused' ..
(if someone will decide to continue with such approach - it could be more
useful to define new value for 'status' parameter :P).
Also, just imaging that OMAP kernel is used with Xen as DomU and how hard will
it be to find and cut off all such tricks :(

Did I miss something?

Quoted 13 lines

Quoted 8 lines

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

OK thanks for explaining it. I'm fine with this patch, Paul may have other issues. The other option would be to use status = "disabled" to not touch the device at all like Paul suggested. I wonder if that's going to break PM on some devices though..

Hi Dave,

Quoted 46 lines · Dave Gerlach

Quoted 45 lines · Grygorii Strashko

Quoted 44 lines · Tony Lindgren

Quoted 43 lines · Dave Gerlach

Quoted 42 lines · Tony Lindgren

Quoted 28 lines · Tony Lindgren

Quoted 15 lines · Dave Gerlach

Quoted 14 lines · Tony Lindgren

Quoted 12 lines · Paul Walmsley

Quoted 7 lines · Dave Gerlach

Introduce a dt property, ti,no-init, that prevents hwmod initialization. Even if a dt node is marked as disabled, hwmod still at least enables the hwmod and programs the sysconfig before attempting to idle it at boot. If an IP has been disabled by the hardware configuration on a platform, this will cause a hang due to writing to inactive registers. This property prevents that from happening by marking the hwmod as _HWMOD_STATE_DISABLED during init.

I'm kind of wondering if hwmod should even touch a device if it's marked as disabled in the DT. Tony, what do you think?

Quoted 8 lines

Quoted 5 lines

Well nothing happens if a device is status = "disabled". No dev entry gets created for it at all and hwmod won't have any data for the device populated. The only way hwmod code could see that device if the device gets it's data from the legacy omap_hwmod_*_data.c instead of DT.

We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP,

Well hwmod does not even know about the IP IO addresses if it's marked with status = "disabled".. Which IP are you having problems with?

Quoted 8 lines

Quoted 4 lines

which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do.

Well hard to say not knowing which module this is.. Pretty much all the modules have drivers and the driver just does pm_runtime_get() on it?

Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address?

Quoted 7 lines

Quoted 7 lines

Quoted 7 lines

Quoted 7 lines

Quoted 1 line

Or am I missing something here?

Perhaps I am mistaken, but from what I understand, all hwmods have _init and _setup called on them, and all hwmods read the IO address regardless of DT status at this point with _init_mpu_rt_base. In _setup, _setup_reset gets called which calls _enable for the hwmod, and this calls both _enable_sysc and _update_sysc_cache which touch the sysconfig register of the IP.

And that's the problem :) What ePar says:
?disabled? - Indicates that the device is not presently operational, but it might become operational in the future (for example, something is not plugged in, or switched off).

and current OF implementation will not register corresponding device in DD core and, as result, drivers will be never ever bound with these devices. As i said before, such devices are invisible/absent/not present, so there are no reasons to touch them at all in Kernel, because result is unpredictable in general. And there are no guarantee that there will be no other issues, even if you'll fix this particular case.

Quoted 11 lines

Quoted 11 lines

Quoted 11 lines

Oh OK, I think you're right. I was thinking of omap_device_build_from_dt(), sorry. Looks like the hwmod IO address data does get populated even for status = "disabled" although the dev entry won't get created and omap_device_build_from_dt() never gets called.

Quoted 4 lines

Normally this is fine regardless of whether or not we are using an IP because the module will wake up for a moment, have it's sysc programmed, and then be put back to sleep later, potentially never to be woken again if we bind no driver for it, which is fine for 99% of cases. In the case of am43x epos evm, you can

^^ if status=?disabled?/"failed" there will be no device and no driver will have been bound :)

Quoted 6 lines

Quoted 6 lines

Quoted 6 lines

Quoted 5 lines

take the same piece of silicon that will boot happily on the gp evm with the rtc hwmod in place and it will hang during boot on the epos evm because the board uses a pin to hold the RTC IP in reset. There is no way to detect this in software, the module can be turned on as normal using the clk_ctrl, but if you touch any of the IP registers you get an abort.

Quoted 1 line

Quoted 1 line

Quoted 1 line

OK sounds like some dts property is needed to signal this.

Seems It might be much more simple to just remove RTC device from DT, as it's disabled and unaccessible == not present:
- add am4372-rtc.dtsi and put RTC device definition there
- include am4372-rtc.dtsi in board files where allowed

Quoted 25 lines

Quoted 11 lines

As I understand, there is device "RTC" and this device has status 'disabled', so there is reasonable question why do we need to touch it at all? The HWMOD is some kind of SoC description, which was needed before DT. Now with DT in place it seems unreasonable to touch any IP block which:
- are not defined in DT
- has status 'disabled'.
in above cases the u-boot has to dial with IP block if it's invisible for Kernel.

Quoted 3 lines

The HWMOD framework intended to reset and put in some predefined states IPs which are visible for the Kernel, so then proper driver can start working with IP or IP will be kept in some low-power state if there is no driver.

Currently we still need this hwmod behavior as not all IPs are in an ideal state for PM by default. Not sure if you saw my last email in this thread but I gave an example for USB hwmod:

If no USB driver is bound even just letting omap_device idle it using the USB_ CLKCTRL in the PRCM will not work properly, because the USB on am33xx expects it's SYSCONFIG STANDBY_MODE to be software supervised, the default state (SMART_STANDBY) does not let the IP go into standby so the IP gets stuck in a partially off state but does not actually shut down as expected.

Quoted 4 lines

So we need to be able to touch the dt nodes even if they are marked as disabled because we need to get the IO address to have access to the SYSCONFIG register. I am not trying to introduce any major new changes to omap_hwmod layer, I am just trying to allow it to work in more situations.

Oh yes! And this happen just due to historical reasons ;)
The HWMOD is ancient thing :P which was created at time when:
- all OMAP's code was built-in
- there were no DT in place.
And it actually was created to describe configuration and integration of HW. But now there is DT which is intended for the same purposes and HWMOD data is still here (as i know) just because process of migration to DT is not fully completed yet. More over, now we have multiplatform; restriction to put SoC's erratas and hacks in kernel; and all drivers going to be converted to loadable modules.

In my opinion, this is not good when we have device marked as 'disabled', but Kernel still tries to access them. More over, we need to completely remove device's definitions from DT to prevent Kernel of touching such devices.

So, let's not make things worse than they are :( and just remove RTC device where it's not needed.

Quoted 31 lines

This flag would only exist to PREVENT any hwmod action from happening in certain cases where we cannot even touch the IP for whatever reason (in the first case that this patch intends to be used for, the RTC IP on am43x-epos-evm which is disabled by the board configuration).

Quoted 24 lines

Such kind of changes really confused :(, because when I'm looking on DT and see - status='disabled' I suppose that such IP will not be touched by Kernel. But it's NOT really 'disabled'. It's kinda 'partially disabled' or 'not present' or 'unused' ..
(if someone will decide to continue with such approach - it could be more
useful to define new value for 'status' parameter :P).
Also, just imaging that OMAP kernel is used with Xen as DomU and how hard will
it be to find and cut off all such tricks :(

Did I miss something?

Quoted 13 lines

Quoted 8 lines

So we need to prevent this from happening but of course we can't selectively choose when the rtc hwmod gets added based on which board we are using so it seemed a DT flag was appropriate to indicate that we do not want to init the rtc IP at all only on this board.

Without this flag in place but with the rtc hwmod added, the am43x-epos-evm fails booting with an imprecise abort.

OK thanks for explaining it. I'm fine with this patch, Paul may have other issues. The other option would be to use status = "disabled" to not touch the device at all like Paul suggested. I wonder if that's going to break PM on some devices though..

That how it should be as for me, but unfortunately, it could break PM :(, because It's common assumption now that Kernel will
reset & disable ALL OMAP's devices regardless of DT.

It could be possible if it will be handled properly outside of the kernel - in u-boot for example.

regards,
-grygorii

RTC hwmod is needed for proper operation of PM features like rtcwake and rtc-only mode so reuse the am33xx rtc hwmod.

Signed-off-by Dave Gerlach <[email protected]>

---
 arch/arm/mach-omap2/omap_hwmod_43xx_data.c | 1 +
 1 file changed, 1 insertion(+)

arch/arm/mach-omap2/omap_hwmod_43xx_data.c +0 -0

index 8eb8592..9070535 100644

Quoted 8 lines · Dave Gerlach

RTC hwmod is needed for proper operation of PM features like rtcwake and rtc-only mode so reuse the am33xx rtc hwmod.

Signed-off-by Dave Gerlach <[email protected]>

---
 arch/arm/mach-omap2/omap_hwmod_43xx_data.c | 1 +
 1 file changed, 1 insertion(+)

arch/arm/mach-omap2/omap_hwmod_43xx_data.c static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = { · line 894

Quoted 11 lines

arch/arm/mach-omap2/omap_hwmod_43xx_data.c +1 -0

index 8eb8592..9070535 100644
@@ -889,6 +889,7 @@ static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = {
 	&am43xx_l4_ls__dss,
 	&am43xx_l4_ls__dss_dispc,
 	&am43xx_l4_ls__dss_rfbi,
+	&am33xx_l4_wkup__rtc,
 	NULL,
 };

Thanks, queued for v4.1.

- Paul

Paul,

Quoted 10 lines · Paul Walmsley

Quoted 8 lines · Dave Gerlach

RTC hwmod is needed for proper operation of PM features like rtcwake and rtc-only mode so reuse the am33xx rtc hwmod.

Signed-off-by Dave Gerlach <[email protected]>

---
 arch/arm/mach-omap2/omap_hwmod_43xx_data.c | 1 +
 1 file changed, 1 insertion(+)

Quoted 13 lines

arch/arm/mach-omap2/omap_hwmod_43xx_data.c static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = { · line 894

Quoted 11 lines

arch/arm/mach-omap2/omap_hwmod_43xx_data.c +1 -0

index 8eb8592..9070535 100644
@@ -889,6 +889,7 @@ static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = {
 	&am43xx_l4_ls__dss,
 	&am43xx_l4_ls__dss_dispc,
 	&am43xx_l4_ls__dss_rfbi,
+	&am33xx_l4_wkup__rtc,
 	NULL,
 };

Thanks, queued for v4.1.

Thanks, but please note as I just commented in Patch 1 of this series, without the ti,no-init flag in place that is introduced there this patch will cause the am43x-epos-evm to fail to boot.

Hi Dave,

Quoted 26 lines · Dave Gerlach

Paul,

Quoted 23 lines · Paul Walmsley

Quoted 13 lines · Dave Gerlach

RTC hwmod is needed for proper operation of PM features like rtcwake and rtc-only mode so reuse the am33xx rtc hwmod.

Signed-off-by Dave Gerlach <[email protected]>

---
 arch/arm/mach-omap2/omap_hwmod_43xx_data.c | 1 +
 1 file changed, 1 insertion(+)

arch/arm/mach-omap2/omap_hwmod_43xx_data.c +0 -0

index 8eb8592..9070535 100644

arch/arm/mach-omap2/omap_hwmod_43xx_data.c static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = { · line 894

Quoted 6 lines

arch/arm/mach-omap2/omap_hwmod_43xx_data.c +1 -0

@@ -889,6 +889,7 @@ static struct omap_hwmod_ocp_if *am43xx_hwmod_ocp_ifs[] __initdata = {
 	&am43xx_l4_ls__dss,
 	&am43xx_l4_ls__dss_dispc,
 	&am43xx_l4_ls__dss_rfbi,
+	&am33xx_l4_wkup__rtc,
 	NULL,
 };

Thanks, queued for v4.1.

Quoted 3 lines

Thanks, but please note as I just commented in Patch 1 of this series, without the ti,no-init flag in place that is introduced there this patch will cause the am43x-epos-evm to fail to boot.

If that's so, shouldn't it appear in the series after patch 3, then? If only patches 1 and 2 are applied, then won't the boot be broken on am43x-epos-evm ?

- Paul

Quoted 15 lines · Paul Walmsley

Quoted 13 lines · Dave Gerlach

Quoted 8 lines · Paul Walmsley

Quoted 4 lines · Dave Gerlach

RTC hwmod is needed for proper operation of PM features like rtcwake and rtc-only mode so reuse the am33xx rtc hwmod.

Signed-off-by Dave Gerlach <[email protected]>

Thanks, queued for v4.1.

Thanks, but please note as I just commented in Patch 1 of this series, without the ti,no-init flag in place that is introduced there this patch will cause the am43x-epos-evm to fail to boot.

Quoted 3 lines

If that's so, shouldn't it appear in the series after patch 3, then? If only patches 1 and 2 are applied, then won't the boot be broken on am43x-epos-evm ?

Hmm yes you are correct that would be the case, seems I should have swapped the order. I've gotten into the habit of putting dt patches last to enable what gets introduced previously, guess it's not always the best thing to do. Thanks for pointing this out.