Re: ACPI P-State platform limit [Was: Re: Cpufreq for opteron]

[Dominik Brodowski <linux@brodo.de>]

On Wed, Aug 27, 2003 at 07:33:00AM +0200, Dominik Brodowski wrote:
> [removed CC:linux-kernel]
> 
> > > I dislike this interaction between ACPI and cpufreq -- it 
> > > should be done
> > > more generally. Let's discuss that seperately, though. And if 
> > > the code is
> > > dead code at the moment.
> > 
> > The dead code has been removed in 1.00.07 of the driver. I am
> > happy to receive suggestions as to better ways of detecting battery
> > versus mains power transitions.
> 
> Currently, the ACPI P-States cpufreq driver does implement the "platform
> limit". However, I'm not really excited about how it works -- and especially
> that it only works with the ACPI P-States cpufreq driver and not with all
> drivers.
> 
> The platform limit [ _PPC ] refers to the states defined in _PSS. This means
> that this knowledge can and should be used independent of the cpufreq driver:
> if the _PPC is, let's say, 2, and accoring to _PSS P2 is 1.2 GHz, a
> "platform limit CPUFREQ_POLICY_NOTIFIER". If the _PPC changes, a
> new cpufreq_reevaluate() function should be called:

I named it cpufreq_update_policy() instead, and you can check the
implementation for it and for the _PPC in:

http://www.brodo.de/cpufreq_tmp/cpufreq-2.6.0-test4-update_policy
and                                                                                
http://www.brodo.de/cpufreq_tmp/acpi-2.6.0-test4-processor_perflib


	Dominik