Re: [PATCH v2 3/4] PM: domains: Drop/restore performance state votes for devices at runtime PM

Ulf Hansson
2021-06-04T07:21:13Z

On Thu, 3 Jun 2021 at 21:08, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 03.06.2021 22:02, Dmitry Osipenko пишет:
> > 03.06.2021 12:34, Ulf Hansson пишет:
> >> A subsystem/driver that need to manage OPPs for its device, should
> >> typically drop its vote for the OPP when the device becomes runtime
> >> suspended. In this way, the corresponding aggregation of the performance
> >> state votes that is managed in genpd for the attached PM domain, may find
> >> that the aggregated vote can be decreased. Hence, it may allow genpd to set
> >> the lower performance state for the PM domain, thus avoiding to waste
> >> energy.
> >>
> >> To accomplish this, typically a subsystem/driver would need to call
> >> dev_pm_opp_set_rate|opp() for its device from its ->runtime_suspend()
> >> callback, to drop the vote for the OPP. Accordingly, it needs another call
> >> to dev_pm_opp_set_rate|opp() to restore the vote for the OPP from its
> >> ->runtime_resume() callback.
> >>
> >> To avoid boilerplate code in subsystems/driver to deal with these things,
> >> let's instead manage this internally in genpd.
> >>
> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> >> ---
> >>
> >> Changes in v2:
> >> - Rebased.
> >> - A few minor cosmetic changes.
> >> - Deal with the error path in genpd_runtime_resume().
> >
> > I tested this on NVIDIA Tegra by removing the boilerplate code from
> > drivers' RPM and haven't noticed any problems, the performance state is
> > dropped/restored as expected. Thank you.
> >
>
> Tested-by: Dmitry Osipenko <digetx@gmail.com>

Thanks a lot, much appreciated!

Kind regards
Uffe