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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 1 Sep 2020 13:57:33 +0200
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Subject: Re: [PATCH] PM: s2idle: Introduce syscore callbacks in s2idle flow
To:     Claude Yen <claude.yen@mediatek.com>
Cc:     "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Douglas Anderson <dianders@chromium.org>,
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On Tue, Sep 1, 2020 at 9:05 AM Claude Yen <claude.yen@mediatek.com> wrote:
>
> This series based on 5.9-rc1
> This patch makes s2idle call existing syscore callbacks. Currently,
> when s2idle is selected as system suspend method, callbacks hooked
> by register_syscore_ops() will not be triggered. This may induce
> unexpected results.

They are not executed by design.

> For example, sched_clock_suspend() was added to s2idle flow in
> commit 3f2552f7e9c5 ("timers/sched_clock: Prevent generic sched_clock
> wrap caused by tick_freeze()") to fix clock wrap problem. However,
> sched_clock_suspend() is originally registered in syscore callback.

I'm not sure why this matters here.

> With this patch, if another syscore callback is needed in s2idle,
> additional migration effort could be saved.

s2idle cannot execute syscore callbacks, because it doesn' take
non-boot CPUs offline and it won't do that.

Thanks!