Re: [PATCH 1/2]cpuidle: makes AMD C1E works in acpi_idle

From: Thomas Gleixner
Date: Tue May 19 2009 - 11:27:00 EST


On Tue, 19 May 2009, Shaohua Li wrote:

> On Tue, May 19, 2009 at 08:55:10PM +0800, Thomas Gleixner wrote:
> > On Tue, 19 May 2009, Shaohua Li wrote:
> >
> > > When AMD C1E is enabled, local APIC timer will stop even in C1. This patch uses
> > > broadcast ipi to replace local APIC timer in C1.
> > >
> > > http://bugzilla.kernel.org/show_bug.cgi?id=13233
> >
> > Hmm. This was addressed before in
> >
> > commit a8d6829044901a67732904be5f1eacdf8539604f (x86: prevent C-states
> > hang on AMD C1E enabled machines)
> >
> > We limit C-States to 1 via acpi_processor_cstate_check().
> >
> > And we have the broadcast logic in c1e_idle() already. We also select
> > c1e_idle as the idle routine, so why is the ACPI code not using this. ?
>
> We used to call pm_idle_save() for C1, which will call c1e_idle. But this is
> removed, guess the reason is we want to do C1 enter per the information gotten
> from BIOS. So this bug is a regression actually. The patch follows the logic
> of c1e_idle().

Hmm, ok. As long as the code does not undo something which was already
set up in c1e_idle() I have no objections.

Thanks,

tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/