Re: [PATCH v3] ARM: tegra: cpuidle: implement cpuidle_state.enter_freeze()

From: Thierry Reding
Date: Mon Jun 29 2015 - 05:02:08 EST


On Thu, Jun 18, 2015 at 09:09:29AM +0200, Tomeu Vizoso wrote:
> On 21 May 2015 at 03:02, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> > On Tuesday, May 19, 2015 04:49:12 PM Tomeu Vizoso wrote:
> >> This callback is expected to do the same as enter() but it has to
> >> guarantee that interrupts aren't enabled at any point in its execution,
> >> as the tick is frozen.
> >>
> >> It will be called when the system goes to suspend-to-idle and will
> >> reduce power usage because CPUs won't be awaken for unnecessary IRQs.
> >>
> >> By setting the CPUIDLE_FLAG_TIMER_STOP flag, we can reuse the same code
> >> for both the enter() and enter_freeze() callbacks.
> >>
> >> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> >> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > Makes sense to me, but I suppose it should go in via arm-soc.
>
> Hi Thierry,
>
> what's the plan regarding merging of this patch?
>
> It needs df8d9ee ("cpuidle: Run tick_broadcast_exit() with disabled
> interrupts") so it doesn't break boot.

By the looks of it the above patch was merged in 4.1, so I can easily
take this through the Tegra tree. The commit message doesn't say whether
or not this fixes a bug. Is this urgent? Should it go into 4.2? It
sounds more like it's a power-saving feature, so 4.3 is probably more
appropriate.

Thierry

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