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From: Ulf Hansson <ulf.hansson@linaro.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	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 1/3] PM: domains: Drop the performance state vote for a device at detach
Date: Thu, 9 Sep 2021 16:45:38 +0200	[thread overview]
Message-ID: <CAPDyKFoV9MOUvu0GLyW-WmNzXbGyFomcug9aTEB-pH32gRHYnQ@mail.gmail.com> (raw)
In-Reply-To: <71618f83-de5b-1180-60f4-8561c4f655a9@gmail.com>

On Thu, 9 Sept 2021 at 15:48, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 07.09.2021 13:16, Ulf Hansson пишет:
> ...
> >>> Also note that a very similar problem exists, *before* the device gets
> >>> attached in the first place. More precisely, nothing prevents the
> >>> performance state from being set to a non-compatible value for an
> >>> always-on HW/device that hasn't been attached yet. So maybe you need
> >>> to set the maximum performance state at genpd initializations, then
> >>> use the ->sync_state() callback to very that all consumers have been
> >>> attached to the genpd provider, before allowing the state to be
> >>> changed/lowered?
> >>
> >> That is already done by the PD driver.
> >>
> >> https://elixir.bootlin.com/linux/latest/source/drivers/soc/tegra/pmc.c#L3790
> >
> > Yes, I already knew that, but forgot it. :-) Thanks for the pointer.
> > Let me rethink the approach.
> >
> > In a way, it kind of sounds like this is a generic problem - so
> > perhaps we should think of adding a ->withdraw_sync_state() callback
> > that can be assigned by provider drivers, to get informed when a
> > consumer driver is getting unbinded.
>
> Not sure, doesn't feel to me that this is necessary for today. A bit too
> cumbersome for a simple sanity-check, IMO.

Maybe, but I can bring it up with the fw_devlinks people to see what they think.

In any case, we should not move forward with $subject patch as is.

Let me think about it.

Kind regards
Uffe

  reply	other threads:[~2021-09-09 14:48 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 [this message]
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

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