linux-kernel - Re: [PATCH 1/2]cpuidle: makes AMD C1E works in acpi

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Message-ID: <20090519150908.GA27513@sli10-desk.sh.intel.com>
Date:	Tue, 19 May 2009 23:09:08 +0800
From:	Shaohua Li <shaohua.li@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"thisistempbox@...oo.com" <thisistempbox@...oo.com>,
	"mingo@...hat.com" <mingo@...hat.com>
Subject: Re: [PATCH 1/2]cpuidle: makes AMD C1E works in acpi_idle

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().

Thanks,
Shaohua
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