Re: [PATCH 5/5] ARM: tegra: cpuidle: use firmware call for powerdown

[Alexandre Courbot]

On 02/06/2014 01:28 AM, Stephen Warren wrote:
> On 01/23/2014 12:39 AM, Alexandre Courbot wrote:
> > On Thu, Jan 23, 2014 at 5:45 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> > > On 01/21/2014 03:10 AM, Alexandre Courbot wrote:
> > > > Invoke the do_idle() firmware call before suspending a CPU so that the
> > > > underlying firmware (if any) can take necessary action.
> > >
> > > > diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c
> > >
> > > > @@ -45,6 +46,8 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
> > > >
> > > >        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> > > >
> > > > +     call_firmware_op(do_idle);
> > > > +
> > > >        cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
> > > >
> > > >        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> > >
> > > Don't you need to have the kernel also *not* do something when entering
> > > idle; doesn't the FW op replace some of the register writes that the
> > > kernel would otherwise be doing?
> >
> > It seems like the operation is actually to inform the firmware that we
> > are going to suspend the CPU. Downstream kernel also uses it that way.
> > But you are right in that we should expect do_idle() to actually
> > perform the suspend operation. Maybe a prepare_idle() operation should
> > be added to the firmware interface for this purpose?
>
> That sounds like a reasonable change. Is it easy to plumb in?

I think so. Will post a v2 of this soon.

Thanks,
Alex.


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