linux-kernel - Re: [PATCH 1/2] CPUFREQ: Enable acpi-cpufreq driver for VIA/Centaur CPUs

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Message-ID: <20090609021551.GG4455@prithivi.gnumonks.org>
Date:	Tue, 9 Jun 2009 10:15:51 +0800
From:	Harald Welte <HaraldWelte@...tech.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Michael S. Zick" <lkml@...ethan.org>,
	Duane Griffin <duaneg@...da.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>
Subject: Re: [PATCH 1/2] CPUFREQ: Enable acpi-cpufreq driver for
	VIA/Centaur CPUs

On Mon, Jun 08, 2009 at 11:35:12AM -0700, Linus Torvalds wrote:
> Hmm. This all really should be just
> 
> 	static int check_est_cpu(unsigned int cpuid)
> 	{
> 		struct cpuinfo_x86 *cpu = &cpu_data(cpuid);
> 		return cpu_has(cpu, X86_FEATURE_EST);
> 	}
> 
> I suspect, with no vendor tests. That's the whole _point_ of CPU features, 
> after all.

That's what I was thinking, too.  If there was no such vendor test, it would
have worked ever since the code was written (the C7 is by far not a new
component, it's around for years).

> If some vendor claims EST but doesn't actually support the EST interfaces, 
> we should just have fixups to clear the bit in the per-vendor cpuinfo 
> code, not in some random driver.

agreed.

> The only thing that makes me nervous about this is how close to 2.6.30 we 
> are. I'd be happier if this was resolved by doing this as a patch 
> post-2.6.30, and then adding 'stable@...nel.org' as a Cc: tag, and 
> backporting it to 2.6.30.1 if no problems appear. 
> 
> It's not like this is a regression, I think.
> 
> Does that sound like a reasonable plan?

Sounds fine with me. But what I would definitely suggest merging before 2.6.30
is the marking e_powersaver EXPERIMENTAL + DANGEROUS patch.

Regards,
-- 
- Harald Welte <HaraldWelte@...tech.com>	    http://linux.via.com.tw/
============================================================================
VIA Free and Open Source Software Liaison
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