From: Ulf Hansson <ulf.hansson@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
Dmitry Osipenko <digetx@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Thierry Reding <thierry.reding@gmail.com>,
Rajendra Nayak <rnayak@codeaurora.org>,
Stephan Gerhold <stephan@gerhold.net>,
Roja Rani Yarubandi <rojay@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Stephen Boyd <sboyd@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/4] PM: domains: Drop/restore performance state votes for devices at runtime PM
Date: Thu, 3 Jun 2021 13:17:18 +0200 [thread overview]
Message-ID: <CAPDyKFofsuY_RAMGsRLtKo=JxJ11DgGqOijZEEf1HEANCvomzg@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFqNNeeMo6+gKgaPtPvgC_NuMxxYKkr+TzyP3vjYoHoDOw@mail.gmail.com>
On Thu, 3 Jun 2021 at 12:31, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> On Thu, 3 Jun 2021 at 11:55, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> > On 03-06-21, 11:34, Ulf Hansson wrote:
> > > 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().
> > >
> > > ---
> > > drivers/base/power/domain.c | 27 +++++++++++++++++++++++++--
> > > include/linux/pm_domain.h | 1 +
> > > 2 files changed, 26 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > > index ef25a5b18587..e5d97174c254 100644
> > > --- a/drivers/base/power/domain.c
> > > +++ b/drivers/base/power/domain.c
> > > @@ -400,6 +400,23 @@ static int genpd_set_performance_state(struct device *dev, unsigned int state)
> > > return ret;
> > > }
> > >
> > > +static int genpd_drop_performance_state(struct device *dev)
> >
> > What about passing the state pointer here? that will simplify the
> > callers to just a call.
>
> Not sure I get that. Can you elaborate a bit more?
>
> >
> > > +{
> > > + unsigned int prev_state = dev_gpd_data(dev)->performance_state;
> > > +
> > > + if (!genpd_set_performance_state(dev, 0))
> > > + return prev_state;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static void genpd_restore_performance_state(struct device *dev,
> > > + unsigned int state)
> > > +{
> > > + if (state)
> >
> > I will skip this check, as we are checking it in
> > genpd_set_performance_state() anyway ?
>
> I don't want us to override OPP votes made by the subsystem/driver
> level runtime PM callbacks. For example, if the drivers manage this
> thing themselves, that should be preserved.
>
> That said, by the check above I want to avoid setting the state to
> zero internally by genpd, if the driver level ->runtime_resume()
> callback has already restored the state.
Ehh, forget about what I said about the ->runtime_resume() callback.
I am mostly trying to avoid restoring a state that is zero, just to be
sure nobody else on some different level outside gendp, have decided
to set a new OPP in-between our calls to
genpd_drop|restore_performance state.
[...]
Kind regards
Uffe
next prev parent reply other threads:[~2021-06-03 11:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 9:34 [PATCH v2 0/4] PM: domains: Avoid boilerplate code for DVFS in subsystem/drivers Ulf Hansson
2021-06-03 9:34 ` [PATCH v2 1/4] PM: domains: Split code in dev_pm_genpd_set_performance_state() Ulf Hansson
2021-06-03 9:34 ` [PATCH v2 2/4] PM: domains: Return early if perf state is already set for the device Ulf Hansson
2021-06-03 9:34 ` [PATCH v2 3/4] PM: domains: Drop/restore performance state votes for devices at runtime PM Ulf Hansson
2021-06-03 9:55 ` Viresh Kumar
2021-06-03 10:31 ` Ulf Hansson
2021-06-03 11:17 ` Ulf Hansson [this message]
2021-06-04 3:53 ` Viresh Kumar
2021-06-04 7:45 ` Ulf Hansson
2021-06-07 4:47 ` Viresh Kumar
2021-06-09 12:25 ` Ulf Hansson
2021-06-03 19:02 ` Dmitry Osipenko
2021-06-03 19:08 ` Dmitry Osipenko
2021-06-04 7:20 ` Ulf Hansson
2021-06-03 9:34 ` [PATCH v2 4/4] PM: domains: Drop/restore performance state votes for devices at system PM Ulf Hansson
2021-06-03 10:20 ` Ulf Hansson
2021-06-03 11:15 ` Mark Brown
2021-06-03 13:48 ` Ulf Hansson
2021-06-08 12:53 ` Stephan Gerhold
2021-06-08 14:08 ` Ulf Hansson
2021-06-08 14:20 ` Mark Brown
2021-06-08 14:39 ` Ulf Hansson
2021-06-08 15:37 ` Stephan Gerhold
2021-06-03 11:12 ` [PATCH v2 0/4] PM: domains: Avoid boilerplate code for DVFS in subsystem/drivers Stephan Gerhold
2021-06-03 15:27 ` Ulf Hansson
2021-06-03 17:14 ` Stephan Gerhold
2021-06-04 7:18 ` Ulf Hansson
2021-06-04 8:23 ` Stephan Gerhold
2021-06-04 10:57 ` Ulf Hansson
2021-06-04 11:50 ` Stephan Gerhold
2021-06-11 16:42 ` Rafael J. Wysocki
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