[PATCH 0/3] CPU frequency scaling addon

[Richard Hughes]

On Mon, 2006-08-14 at 19:54 +0200, Holger Macht wrote:
> On Mon 14. Aug - 18:48:23, Richard Hughes wrote:
> > On Sat, 2006-08-12 at 12:34 +0200, Holger Macht wrote:
> > > Just save the mail. diff ignores everything except the diff.
> > 
> > Yes, that worked, thanks.
> > 
> > Apart from looking in /org/freedesktop/Hal/devices/computer:info.addons
> > for the hald-addon-cpufreq addon name, is there a way for desktop
> > programs to find out if HAL can manage CPU scaling?
> > 
> > Maybe we need a power_management.can_do_cpu_scaling key or something
> > more suitable.
> 
> 
> Maybe checking if the CPUFreq methods are listed in the
> org.freedesktop.Hal.Device.SystemPowerManagement.method_names key is
> enough?
> 
> And if so, use the GetCPUFreqAvailableGovernors method to check if there
> are governors to be used.

Hmm. It's making it a bit difficult for applications to work out "can I
control the cpu frequency with HAL" but I guess it works for me.

> > 
> > I also noticed the addon doesn't exit if the computer doesn't have
> > a /sys/devices/system/cpu/cpu0/cpufreq/ directory which would probably
> > be a good thing.
> 
> But if a cpufreq driver (e.g. speedstep_centrino) or a governor is loaded
> after the addon exited but during runtime of HAL, the system suddenly gets
> CPUFreq capabilities but it couldn't be used anymore.

Yes, I wondered this. I figured the modules normally would be loaded
before HAL started and thus wouldn't be a problem. Agreed this wouldn't
be ideal.

Is there a way we can get an event from the kernel like "new cpufreq
module inserted" so can can then match and run the addon if not already
started?

Richard.