linux-kernel - Re: [PATCH V2 5/6] PM / domain: Save/restore performance state at runtime suspend/resume

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Message-ID: <m21suw4bfp.fsf@baylibre.com>
Date:   Fri, 17 Feb 2017 15:58:18 -0800
From:   Kevin Hilman <khilman@...libre.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, ulf.hansson@...aro.org,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        sboyd@...eaurora.org, nm@...com, robh+dt@...nel.org,
        lina.iyer@...aro.org, rnayak@...eaurora.org
Subject: Re: [PATCH V2 5/6] PM / domain: Save/restore performance state at runtime suspend/resume

Viresh Kumar <viresh.kumar@...aro.org> writes:

> With runtime PM, the devices get suspended while the system is up and
> running in order to save power. At such times, it is important to
> re-evaluate the required performance state of the domain, in order to
> choose a lower state if possible.
>
> This patch updates the genpd suspend/resume callbacks to do that.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

Doesn't this assume that a device in the domain would need to change
performance state while runtime suspended.  How would that happen?

Rather than adding this here, I would think that drivers would instead
remove any QoS requests before going into runtime suspend, which would
trigger an update before runtime suspending.

Kevin