From: Viresh Kumar <viresh.kumar@linaro.org>
To: Ulf Hansson <ulf.hansson@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: Fri, 4 Jun 2021 09:23:12 +0530 [thread overview]
Message-ID: <20210604035312.jp2gshfigsodwvcg@vireshk-i7> (raw)
In-Reply-To: <CAPDyKFofsuY_RAMGsRLtKo=JxJ11DgGqOijZEEf1HEANCvomzg@mail.gmail.com>
On 03-06-21, 13:17, Ulf Hansson wrote:
> On Thu, 3 Jun 2021 at 12:31, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > > > +static int genpd_drop_performance_state(struct device *dev)
> > > > +{
> > > > + 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.
What stops the core to call genpd_drop_performance_state() in the
first place here, if the driver was doing its own thing ? If that gets
called, then restore should be without any checks IMO. The state
should already be 0 at this point of time, I don't know why this will
get called again with state 0, but it will have no effect.
Can you give some sort of flow sequence where I can see the problem a
bit more clearly ?
--
viresh
next prev parent reply other threads:[~2021-06-04 3:53 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
2021-06-04 3:53 ` Viresh Kumar [this message]
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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