Radeon power management and KMS

François Cami fdc-lists at fcami.net
Sat Nov 20 11:03:19 UTC 2010


On Sat, Nov 20, 2010 at 8:29 AM, Christoph Frieben
<christoph.frieben at googlemail.com> wrote:
> What's up with Radeon power management under KMS? The most recent
> related entries in the kernel change log read:
>
> * Sun Jun 13 2010 Kyle McMartin <kyle redhat com> 2.6.34-34
> - Provide a knob to enable radeon_pm to allow users to test
>  that functionality. Add radeon.pm=1 to your kernel cmdline
>  in order to enable it. (It still defaults to off though.)
>
> However, kernel option radeon.pm has no effect
> Has support for this feature been discarded in Fedora kernels?

These changelog entries were for 2.6.34 (f13), and I take it you're
running f14+ and looking at 2.6.35.
Both dynpm and radeon_pm were eliminated from 2.6.35. Radeon power
management features are now controlled via sysfs.

First, select a power management method, by echoing "dynpm" or
"profile" to /sys/class/drm/card-0/device/power_method.
It seems that dynpm can produce display artifacts, so you probably
want to choose "profile" (which is the default).
If you choose the profile method, then you can switch from the
"default", "auto", "low", "mid", "high"  profiles by echoing the
relevant keyword to /sys/class/drm/card-0/device/power_profile.

More info there:
http://wiki.x.org/wiki/RadeonFeature
Relevant commit diff:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=ce8f53709bf440100cb9d31b1303291551cf517f

François


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