Re: [PATCH 5/6] intel_idle: Add ->enter_freeze callbacks

Rafael J. Wysocki
2015-03-04T23:55:03Z

On Thursday, March 05, 2015 07:50:26 AM Li, Aubrey wrote:
> On 2015/2/13 0:24, Rafael J. Wysocki wrote:
> > On Thursday, February 12, 2015 02:26:43 PM Peter Zijlstra wrote:
> >>
> >> Why bother with enter_freeze() for any but the deepest state (C6 in this
> >> case)?
> >
> > User space may disable the deepest one (and any of them in general) via sysfs
> > and there's no good reason to ignore its choice in this particular case while
> > we're honoring it otherwise.
> >
> > So the logic is basically "find the deepest one which isn't disabled" and
> > setting the pointers costs us nothing really.
> >
>
> If the user has chance to disable C6 via /sys, that means c6 works?
> Shouldn't we ignore user space setting during freeze? Otherwise, we will
> lost S0ix?

We can't ignore it, because we don't know the reason why the state was
disabled.

It may just not work reliably enough on the given platform.

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.