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Date: Thu, 9 Sep 2021 16:48:49 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: "Rafael J . Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
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 1/3] PM: domains: Drop the performance state vote for a
device at detach
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.
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