Re: [Acpi4asus-user] [PATCH 1/1] cpufreq: eeepc 900 frequency scaling driver

Matthew Garrett
2009-04-05T10:21:26Z

On Sun, Apr 05, 2009 at 09:43:40AM +0200, Corentin Chary wrote:
> >> Could it happen that upcoming machines provide this interface (the two ACPI
> >> functions) and also can do real CPU frequency/volt switching, e.g. via
> >> acpi-cpufreq?
> >
> > Probably this interface is a solution specific to machines based on the
> > celeron M: I don't even know if other 'old' models provide the same
> > interface.
>
> Hi,
> We I just received another patch for that (adding a cpufv file in
> sysfs) and I don't really know what to do.
>
> As Grigori Goronzy said, using cpufreq in not a good idea:

I'm not sure I agree. It's clear that ondemand and conservative aren't
sensible choices with the driver, but beyond that...

> > 3) It looks like it is impossible to use more than one cpufreq driver
> > per CPU. This effectively means you can either use the regular ACPI
> > frequency scaling, which switches between multipliers, or SHE. That's
> > unacceptable. SHE is not intended to replace the regular frequency
> > scaling, but to complement it.

I don't think there's a terribly good reason to use the SHE methods if
the CPU supports speedstep. 945 will automatically drop the frontside
bus in the deepest P states. I'd be surprised if it gave any real world
benefits on the atom based systems.

--
Matthew Garrett | mjg59@srcf.ucam.org