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From: Ulf Hansson <ulf.hansson@linaro.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Linux PM <linux-pm@vger.kernel.org>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Rajendra Nayak <rnayak@codeaurora.org>,
	Stephan Gerhold <stephan@gerhold.net>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd
Date: Thu, 9 Sep 2021 16:39:54 +0200	[thread overview]
Message-ID: <CAPDyKFoFCVcjrGXQ56y0iSNPhE8-orpZiHvnAQTQW1b8oW4f5A@mail.gmail.com> (raw)
In-Reply-To: <1ca9a2d5-e89a-5bbd-2ecc-01f1c4a820ae@gmail.com>

On Thu, 9 Sept 2021 at 15:48, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 07.09.2021 12:57, Ulf Hansson пишет:
> > I don't mind extending the genpd API, but it needs to serve a good purpose.
> >
> > As I said earlier, genpd doesn't know nor can control how the consumer
> > driver deploys runtime PM. Unfortunately, that also includes genpd
> > providers, as the behavior isn't a platform or PM domain specific
> > thing. This means genpd needs to be generic enough so it works for all
> > cases.
> >
> > In the $subject patch, we rely on the pm_runtime_suspended() check in
> > dev_pm_genpd_set_performance_state(), which should work for all cases,
> > even if it may be sub-optimal for some scenarios.
> >
> > Note that, in the approach your suggested [1],
> > pm_runtime_status_suspended() is used instead. This doesn't work when
> > a consumer driver doesn't enable runtime PM - or calls
> > pm_runtime_set_active() during ->probe(), because
> > genpd_runtime_resume() won't be invoked to restore the gpd->rpm_state.
> >
> > That said, I wouldn't mind to simply skip adding the
> > ->dev_get_performance_state() all together, if that is what you
> > prefer? In this way, it becomes the responsibility for the consumer
> > driver to do right thing, with the cost of some boilerplate code added
> > in its ->probe() routine.
>
> Until a day ago, it wasn't clear to me that consumer drivers now can set
> up rpm_pstate during probe(), which is a cleaner solution that works
> well. So let's skip adding the questionable ->dev_get_performance_state().
>
> The boilerplate code in the probe() is minimal in comparison to a
> previous variant with the state-syncing done by rpm-resume callbacks of
> consumer drivers, it's good enough.

Alright, that sounds good to me as well.

I am happy to help with review of the consumer driver changes, just
keep me posted.

Thanks and kind regards
Uffe

  reply	other threads:[~2021-09-09 14:47 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 10:16 [PATCH 0/3] PM: domains: Improvements for performance states in genpd Ulf Hansson
2021-09-02 10:16 ` [PATCH 1/3] PM: domains: Drop the performance state vote for a device at detach Ulf Hansson
2021-09-03  6:01   ` Dmitry Osipenko
2021-09-03  8:22     ` Ulf Hansson
2021-09-03  9:58       ` Dmitry Osipenko
2021-09-03 14:03         ` Ulf Hansson
2021-09-05  8:26           ` Dmitry Osipenko
2021-09-06 10:24             ` Ulf Hansson
2021-09-06 14:11               ` Dmitry Osipenko
2021-09-06 17:34                 ` Ulf Hansson
2021-09-06 19:33                   ` Dmitry Osipenko
2021-09-07 10:16                     ` Ulf Hansson
2021-09-09 13:48                       ` Dmitry Osipenko
2021-09-09 14:45                         ` Ulf Hansson
2021-09-02 10:16 ` [PATCH 2/3] PM: domains: Restructure some code in __genpd_dev_pm_attach() Ulf Hansson
2021-09-02 10:16 ` [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd Ulf Hansson
2021-09-03  6:00   ` Dmitry Osipenko
2021-09-03  8:55     ` Ulf Hansson
2021-09-03 10:06       ` Dmitry Osipenko
2021-09-03 14:09         ` Ulf Hansson
2021-09-05  9:11           ` Dmitry Osipenko
2021-09-06 10:53             ` Ulf Hansson
2021-09-06 14:35               ` Dmitry Osipenko
2021-09-07  3:40                 ` Viresh Kumar
2021-09-07  8:10                   ` Dmitry Osipenko
2021-09-07  9:57                 ` Ulf Hansson
2021-09-09 13:48                   ` Dmitry Osipenko
2021-09-09 14:39                     ` Ulf Hansson [this message]
2021-09-10 11:24                       ` Dmitry Osipenko

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