Re: [PATCH v5 2/2] PM / Domains: use device's next wakeup to determine domain idle state

[Lina Iyer <ilina@codeaurora.org>]

On Thu, Nov 19 2020 at 02:57 -0700, Ulf Hansson wrote:
>On Mon, 16 Nov 2020 at 16:57, Lina Iyer <ilina@codeaurora.org> wrote:
>>
>> On Fri, Nov 13 2020 at 03:34 -0700, Ulf Hansson wrote:
>> >On Wed, 11 Nov 2020 at 17:51, Lina Iyer <ilina@codeaurora.org> wrote:
>> >>
>> >> On Tue, Nov 10 2020 at 03:02 -0700, Ulf Hansson wrote:
>> >> >On Mon, 9 Nov 2020 at 18:41, Lina Iyer <ilina@codeaurora.org> wrote:
>> >> >>
>> >> >> On Mon, Nov 09 2020 at 08:27 -0700, Ulf Hansson wrote:
>> >> >> >On Fri, 6 Nov 2020 at 17:48, Lina Iyer <ilina@codeaurora.org> wrote:
>> >> >> >>
>> >> >> [...]

>>
>> What you are suggesting is that, we should not power down the domain in
>> such a case. This would be a really hard problem to debug when a device
>> leaves a stale wakeup behind and we no longer power off the domain
>> because of that. Tracking that back to the device will be a monumental
>> effort. Ignoring the next wakeup though might involve a power/perf
>> penalty (no worse than today), but we would not have a difficult problem
>> to solve.
>
>Hmm, you have a good point!
>
>Additionally, I guess it should be a rather seldom situation, as in
>principle the wakeup irq should have been triggered already.
>
>That said, I am okay to stick with your suggested approach.
>
>Although, please add a comment in the code, to make it clear that the
>behaviour is deliberate. Perhaps we should also clarify the function
>description of dev_pm_genpd_set_next_wakeup() (in patch1) to make the
>behaviour more clear for the user.
>
Sure, will update with comments.
>>

Let's revisit the patch again after I repost, to make sure this is what
we want, atleast for now.

Thanks for your review, Ulf.

--Lina