fglrx in Ubuntu 10.10: disable underscan

Do you see black borders on your TV when you connect your Linux HTPC with ATI Radeon chipset/card? Usually you would be able to change overscan/underscan settings in the graphical ATI tool – but my plasma is detected as a projector, some underscan is applied and the slider to correct it is missing.

The solution lies in the command-line tool aticonfig. It allows you to set the relative screen position and the absolute screen size. Create a new file containing this script:

aticonfig --set-dispattrib=dfp1,positionX:0
aticonfig --set-dispattrib=dfp1,positionY:0
aticonfig --set-dispattrib=dfp1,sizeX:1920
aticonfig --set-dispattrib=dfp1,sizeY:1080

and make it executable. Now configure it as a “startup application” in the Ubuntu preferences. There’s a catch though: you need to find out the name of your display device first. Mine is called “dfp1”. Have a look at your /var/log/Xorg.0.log and find the line similar to

[    25.483] (II) fglrx(0): Connected Display0: DFP1

and insert the correct name into the script. Also make sure you set the correct display resolution. Run the script or log off and back on, and the black borders should be gone.