How to make use of Graphics Chips Power Management features

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Revision as of 18:30, 24 October 2005 by Johannes (Talk | contribs) (DynamicClocks in the Radeon Xorg driver)

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Power Saving With A Framebuffer Console

In order to use the dynamic GPU clock-scaling similar to what X.org has, you need to use the radeonfb kernel module. You'll need to enable the CONFIG_FB_RADEON in your kernel configuration. If setup correctly you should see something like the following in your kernel log:

radeonfb: Dynamic Clock Power Management enabled

DynamicClocks in the Radeon Xorg driver

The xorg X server has support for a power saving feature from ATI called PowerPlay. Xorg calls this feature DynamicClocks. It can be enabled in the server by adding Option "DynamicClocks" "on" in the Device section in /etc/X11/xorg.conf

Section "Device"
       Identifier  "Videocard0"
       Driver      "radeon"
       VendorName  "IBM Thinkpad"
       BoardName   "ATI Radeon Mobility M9"
       Option      "DynamicClocks" "on"
EndSection

With this option enabled, the X11 server should print (/var/log/Xorg.0.log):

(**) RADEON(0): Option "DynamicClocks" "on"
(II) RADEON(0): Dynamic Clock Scaling Enabled
NOTE!
Enabling DynamicClocks crashes some models. If the CPU is entering one of the lower power states (C3 or lower) during Xorg startup the display may stay black. As a workaround disable DynamicClocks in Xorg and use Rovclock instead. But it does not scale the clocks to match the workload.

How to use it

After enabling it, my first question was how do I control it? After reading about it, the answer is: you don't have to, it manages the power consumption for you.\

X.org on Debian

Because debian doesn't have X.org yet - Installing a non-intrusive X.org server on Debian.

Update: X.org has made it into Debian. See: [1]

There are also sarge backports available here or here.

Add the following line to your repository list:

deb http://people.debian.org/~nobse/xorg-x11/ sarge main

External Sources