Re: [PATCH] PM / suspend: Always use deepest C-state in the "freeze" sleep state

[Daniel Lezcano]

On 05/12/2014 04:19 PM, Li, Aubrey wrote:
> On 2014/5/12 22:08, Daniel Lezcano wrote:
> > On 05/05/2014 12:51 AM, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > >
> > > If freeze_enter() is called, we want to bypass the current cpuidle
> > > governor and always use the deepest available (that is, not disabled)
> > > C-state, because we want to save as much energy as reasonably possible
> > > then and runtime latency constraints don't matter at that point, since
> > > the system is in a sleep state anyway.
> > >
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > ---
> > >
> > > This is on top of https://patchwork.kernel.org/patch/4071541/ .
> >
> > Wouldn't make sense to revisit play_dead instead ?
> play_dead() is broken.
>
> Even if it works, we still should rely on cpuidle driver to place the
> CPUs into the deepest c-state, because there is no architectural way to
> enter deepest c-state and what play_dead() does is a bad assumption.

Ok, let me rephrase it. Why not revisiting cpuidle_play_dead instead ?


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