Bug#508066: xserver-xorg-video-radeon: external display not work on ATI Technologies Inc Radeon Mobility U1
Robert Heel wrote:
> No, no change... The monitor also would display an error message in case of a not supported signal.
> Tried ubuntu, too - same problem.
> Is there a possibility to deactivate xrandr to switch back to old functionality?
No, you can't disable RandR 1.2.
But if you happen to know which mode your internal and external display
like, so can use ModeLine+PreferredMode to enforce them by default in
xorg.conf. See http://wiki.debian.org/XStrikeForce/HowToRandR12 sections
III.1 and III.5.