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From: Dmitry Osipenko <digetx@gmail.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
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: Fri, 10 Sep 2021 14:24:38 +0300	[thread overview]
Message-ID: <8dadc395-e7f4-9dcc-b484-60c119063007@gmail.com> (raw)
In-Reply-To: <CAPDyKFoFCVcjrGXQ56y0iSNPhE8-orpZiHvnAQTQW1b8oW4f5A@mail.gmail.com>

09.09.2021 17:39, Ulf Hansson пишет:
> 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.

Thank you and Viresh for the help, very appreciate it!

      reply	other threads:[~2021-09-10 11:24 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
2021-09-10 11:24                       ` Dmitry Osipenko [this message]

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