How to make use of Graphics Chips Power Management features
Contents
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
You do not need to do anything else, it dynamically manages the power consumption itself.
Problem with vbetool
When vbetool is used to restore the display state (as done by some suspend/resume scripts), the setting of DynamicClocks is forgotten and the GPU will consume more power until the next X server startup. You can manually enable DynamicTools again by starting a blank second X server (e.g., by running # X :1
) and then exiting it via CtrlAltBackspace.
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