[PATCHv2 8/8] arm: omap3: prevent per_clkdm from attempting manual domain transitions

[Shilimkar, Santosh]

On Thu, Feb 16, 2012 at 8:53 PM, Tero Kristo <t-kristo at ti.com> wrote:
> On Thu, 2012-02-16 at 15:15 +0200, Tero Kristo wrote:
>> On Thu, 2012-02-16 at 15:27 +0530, Shilimkar, Santosh wrote:
>> > On Thu, Feb 16, 2012 at 2:27 PM, Tero Kristo <t-kristo at ti.com> wrote:
>> > > On Wed, 2012-02-15 at 11:37 -0800, Kevin Hilman wrote:
>> > >> Tero Kristo <t-kristo at ti.com> writes:
>> > >>
>> > >> > Attempting this will cause problems especially with off-mode enabled.
>> > >>
>> > >> Please be more verbose about the problems seen, and the root cause(s).
>> > >>
>> > >
>> > > I was actually looking forward for some help with this commit message,
>> > > as I am still not quite sure what is going on in here. :) Here is the
>> > > log for suspend (btw, cam_pwrdm does not go to off in mainline yet, but
>> > > I think that is probably fixed by the patch from Paul,
>> > > omap_set_pwrdm_state() does not work properly.) The warning comes out
>> > > after wakeup from off-mode, and it is triggered by the disabling of
>> > > autodeps before off-mode entry.
>> > >
>> > This mostly indicates that one of the per clock-domain module
>> > clock turning ON seems to be not working well with auto deps
>> > disabled. This leads to interconnect violation.
>> >
>> > if not tried already, can you put the per_clockdomain in SW_WKUP
>> > in the low power code early resume path and see if this
>> > error goes away.
>>
>> This seems to get rid of the dump also. It looks like some driver resume
>> is not behaving nicely, I am trying to pinpoint the culprit currently
>> and see whether it can provide more info.
>
> Okay, I have some more info about this now.
>
> What happens is that when entering off-mode, PER domain remains OFF even
> during the execution of the exit phase from omap_sram_idle. Adding a
> manual SW_WKUP it comes up and there are no issues. If autodeps are
> enabled on the domain, it comes back from off mode as active.
>
> Looking further in the code, we have this at the end of omap_sram_idle:
>
>        if (per_next_state < PWRDM_POWER_ON) {
>                per_prev_state = pwrdm_read_prev_pwrst(per_pwrdm);
>                omap2_gpio_resume_after_idle();
>                wake_per();
>                if (per_prev_state == PWRDM_POWER_OFF)
>                        omap3_per_restore_context();
>        }
>
> ... which seems to assume that per domain is on. Gpio code does not
> control any clocks currently, as it only requires the interface clock to
> be on, and as this is autoidled....
>
> Any comments how we should handle this? Shall we just keep these two
> patches for handling this or add some different hackery for the gpio
> issue?
>
Good. I thought too that issue will disappear.
The issue is pretty clear. Technically every driver pm_runtime() code should
be able to manage a clock->clockdomain->power domain power up/down
sequence. That should work without auto deps.

Do you narrowed down which driver resume is creating the dump ?
UART , GPIO ?

Regards
Santosh