Re: [PATCH 07/13] OMAP PM: early init of the pwrdms states

[Jean Pihet <jean.pihet@newoldbits.com>]

On Fri, Jul 29, 2011 at 10:08 AM, Todd Poynor <toddpoynor@google.com> wrote:
> On Thu, Jul 28, 2011 at 10:30:14AM +0200, jean.pihet@newoldbits.com wrote:
>> From: Jean Pihet <j-pihet@ti.com>
>>
>> The powerdomains next states are initialized in pwrdms_setup as a
>> late_initcall. Because the PM QoS devices constraint can be requested
>> early in the boot sequence, the power domains next states can be
>> overwritten by pwrdms_setup.
>>
>> This patch fixes it by initializing the power domains next states
>> early at boot, so that the constraints can be applied.
>> Later in the pwrdms_setup function the currently programmed
>> next states are re-used as next state values.
>>
>> Applies to OMAP3 and OMAP4.
>>
>> Tested on OMAP3 Beagleboard and OMAP4 Pandaboard in RET/OFF using
>> wake-up latency constraints on MPU, CORE and PER.
>>
>> Signed-off-by: Jean Pihet <j-pihet@ti.com>
>> ---
> ...
>> diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
>> index 9af0847..63c3e7a 100644
>> --- a/arch/arm/mach-omap2/powerdomain.c
>> +++ b/arch/arm/mach-omap2/powerdomain.c
>> @@ -108,6 +108,9 @@ static int _pwrdm_register(struct powerdomain *pwrdm)
>>       pwrdm->state = pwrdm_read_pwrst(pwrdm);
>>       pwrdm->state_counter[pwrdm->state] = 1;
>>
>> +     /* Early init of the next power state */
>> +     pwrdm_set_next_pwrst(pwrdm, PWRDM_POWER_RET);
>> +
>
> Wanted to check that it's OK to initialize the next state of a power
> domain to RETENTION early in the boot sequence.  I believe patches
> have been previously discussed that set the state to ON to ensure the
> domain doesn't go to a lower state, and possibly lose context, before
> the PM subsystem is setup to handle it?  Not sure, thought maybe worth
> a doublecheck.
Indeed I need to check the behavior for OMAP3 & 4 which seem to
initialize the pwrdm states differently.
BTW the patch that inits all pwrdms to ON is not yet in l-o master
that is why I (lazily) submitted this one for now.

>
>
> Todd
>
>

Jean
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