linux-kernel - Re: [PATCH 1/1] cpufreq: eeepc 900 frequency scaling driver

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Message-ID: <20090316082952.GA1963@elf.ucw.cz>
Date:	Mon, 16 Mar 2009 09:29:52 +0100
From:	Pavel Machek <pavel@....cz>
To:	Len Brown <lenb@...nel.org>
Cc:	Matthew Garrett <mjg@...hat.com>,
	Cristiano Prisciandaro <cristiano.p@...net.ch>,
	Dave Jones <davej@...hat.com>, cpufreq@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] cpufreq: eeepc 900 frequency scaling driver

On Mon 2009-03-16 00:24:18, Len Brown wrote:
> 
> On Tue, 2 Dec 2008, Pavel Machek wrote:
> 
> > On Tue 2008-12-02 16:15:21, Matthew Garrett wrote:
> > > On Sun, Nov 23, 2008 at 07:04:09PM +0100, Pavel Machek wrote:
> > > 
> > > > Is this really needed? Could we simply talk to the cpu directly,
> > > > without help of ACPI?
> > > 
> > > No. The ACPI write ends up talking to the embedded controller and some 
> > > io ports.
> > 
> > Oops... I always knew that eee-s are broken by design (reporting
> > battery percent as mWh, etc...) but I did not realize how bad it
> > is. (ACPI has perfectly standard cpu frequency scaling interface, even
> > if it is not used too often these days....)
> 
> Huh?
> 
> What cpufreq driver is deployed more broadly than acpi-cpufreq?
> AFAIK, Linux uses it on nearly every ACPI compliant Intel-based
> system that has frequency scaling.

Problem seems to be that eee uses custom ACPI methods
(switch_to_fast_clock(0/1)-like), not anything acpi-cpufreq could
drive... Broken by design :-(.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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