[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 9 Sep 2021 16:48:36 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Linux PM <linux-pm@...r.kernel.org>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Jonathan Hunter <jonathanh@...dia.com>,
Thierry Reding <thierry.reding@...il.com>,
Rajendra Nayak <rnayak@...eaurora.org>,
Stephan Gerhold <stephan@...hold.net>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state()
callback to genpd
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.
Powered by blists - more mailing lists