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

Harald Welte
2009-06-08T18:10:24Z

On Mon, Jun 08, 2009 at 02:16:20PM +0100, Matthew Garrett wrote:
> On Mon, Jun 08, 2009 at 06:27:54PM +0800, Harald Welte wrote:
> > The VIA/Centaur C7, C7-M and Nano CPU's all support ACPI based cpu p-states
> > using a MSR interface. The Linux driver just never made use of it, since in
> > addition to the check for the EST flag it also checked if the vendor is Intel.
>
> Hm. Is the MSR interface compatible with the Intel one?

Yes, it is intended to be. If you know of any public intel spec on the actual
MSR values, I'd be happy to have a look and compare it with Centaur's specs.

VIA/Centaur specs are being prepared for public release, but it will probably
take longer than we can responsibly delay fixing this bug.

> I'm guessing so based on the est flag being present. Maybe we should just
> drop the intel check and only look for CPUs which claim est support.

I think that might be the right decision.

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