Re: [RFC] OMAP3: CPUIDLE & PM: Modifications and fixes

[jouni.hogander@nokia.com (Högander Jouni)]

"ext Paul Walmsley" <paul@booyaka.com> writes:

> Hello Jouni,
>
> On Mon, 11 Aug 2008, Högander Jouni wrote:
>
>> "ext Paul Walmsley" <paul@booyaka.com> writes:
>>
>> > Could you explain a little further why PER would have a wakeup dependency 
>> > on CORE?  Is this something that we should only enable under certain 
>> > conditions, e.g., latency requirements for a device in PER?
>> 
>> This is done to make sure we don't loose any gpio interrupts: GPIO
>> wakeup/interrupt doesn't work for GPIOs in PER domain if PER is not
>> active.
>
> I'm probably misunderstanding something, but ... wouldn't it better to 
> just keep PER powerdomain ON all the time when PER GPIOs are enabled for 
> interrupts?  It seems possible for PER to go to retention or OFF even with 
> the CORE wkdep in place, which would result in a period of time where the 
> interrupts would be missed, no?

No, it won't, PER goes sleep state only if CORE goes
too. There is a hardware sleepdep between PER and CORE, thanks to
Rajendra for pointing this out some time ago. This way there are all
the time some wakeup mechanism available for PER gpios
(gpio/iopad). Leaving PER ON would increase consumption.

>
>> >> 3. Deny hwsup mode before writing next pwrst state
>> >
>> > I missed this part of the patch - could you point me at that
>> > section?
>> 
>> Patch changes code to use set_pwrdm_state from pm34xx.c instead of
>> pwrdm_set_next_pwrst from powerdomain code. That function contains
>> denying hwsup mode.
>
> Ah, okay.
>
>
> - Paul

-- 
Jouni Högander

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