linux-kernel - Athlon L110 CPU and powernow-k8

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Message-ID: <1271450458.6794.33.camel@tomoyo>
Date:	Fri, 16 Apr 2010 22:40:58 +0200
From:	Josselin Mouette <joss@...ian.org>
To:	linux-kernel@...r.kernel.org
Subject: Athlon L110 CPU and powernow-k8

Hi,

I have a Packard-Bell Dot-M/A which is based on an Athlon L110 CPU, and
I noticed that powernow-k8 does not recognize this CPU’s frequencies,
which leads to an insane power consumption, leaving it at 1,2 GHz
permanently.

The Gateway LT31, based on the same CPU, has the same issue, as reported
Krists Krilovs: http://www.pow.za.net/

In both cases, the issue is the same: the DSDT table provided by the
BIOS does not include the P-states. Waiting for a hypothetical BIOS
update that would fix this bug requires some faith that I don’t have. It
is possible to work around this by compiling the kernel with a custom
DSDT table with appropriate P-states patched in, however I consider this
a developer hack. (Krists Krilovs has the patched DSDT for the LT31, and
I can provide the one for the Dot-M/A upon request as well - I used the
same P-states.)

I wonder what is possible to do to support this CPU correctly in the
kernel. The only sane solution I can think of is to hardcode the
P-states for this CPU model in the powernow-k8 driver itself. 

I’m quite a newbie when it comes to ACPI, but I can provide any
information that could help to fix this. If you think it’s feasible by a
random hacker, I can also have a look given the correct pointers.

Cheers,
-- 
 .''`.      Josselin Mouette
: :' :
`. `'  “If you behave this way because you are blackmailed by someone,
  `-    […] I will see what I can do for you.”  -- Jörg Schilling

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