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 12:31:02 +0200 [thread overview]
Message-ID: <CAPDyKFqNNeeMo6+gKgaPtPvgC_NuMxxYKkr+TzyP3vjYoHoDOw@mail.gmail.com> (raw)
In-Reply-To: <20210603095538.b2t3cq25tq7v7kih@vireshk-i7>
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.
>
> > + genpd_set_performance_state(dev, state);
> > +}
> > +
> > /**
> > * dev_pm_genpd_set_performance_state- Set performance state of device's power
> > * domain.
> > @@ -842,7 +859,8 @@ static int genpd_runtime_suspend(struct device *dev)
> > {
> > struct generic_pm_domain *genpd;
> > bool (*suspend_ok)(struct device *__dev);
> > - struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
> > + struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
> > + struct gpd_timing_data *td = &gpd_data->td;
> > bool runtime_pm = pm_runtime_enabled(dev);
> > ktime_t time_start;
> > s64 elapsed_ns;
> > @@ -899,6 +917,7 @@ static int genpd_runtime_suspend(struct device *dev)
> > return 0;
> >
> > genpd_lock(genpd);
> > + gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
>
> So this will become:
>
> genpd_drop_performance_state(dev, &gpd_data->rpm_pstate);
>
> and it can have return type of void.
See more above, about the reason why it looks like this. Hopefully
that explains it.
Kind regards
Uffe
next prev parent reply other threads:[~2021-06-03 10:31 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 [this message]
2021-06-03 11:17 ` Ulf Hansson
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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