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

Tom Hughes
2008-11-24T16:47:19Z

Thomas Renninger wrote:

> Oh, they are part of this general Asus \\_SB.ATKD device, which is only
> used by asus_laptop.c until now?

I believe eeepc-laptop is also accessing the same device - at least it
is calling other methods defined in the same part of the DSDT although
it doesn't seem to be using that name to reach them.

> Some more questions:
> Why are they providing their own cpufreq interface and not following the
> spec (providing _PSS, ..)?
> Could it be that you are only throttling the CPU?
>
> Are these functions already used by the ACPI tables internally?
> - could be dangerous
> - could be helpful -> Is there some upper level device/interface in ASL?
>
> 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?

Well the recent eee's are all Atom based, which I assume has proper
SpeedStep support but the early ones have a Celeron processor.

The history is that the original eee, the 701, was underclocking a
900MHz CPU at 630Mhz and in the 900 they added support for running at
full speed with the BIOS able to switch between the two speeds. I assume
it just changes the clock multiplier or something.

The 901 and later of course use the Atom and presumably work differently.

Tom

--
Tom Hughes (tom@compton.nu)