To test the plug and play capability of your driver you may want to use a minimal or no xorg.conf. However on some machines the current level of plug and play support may trigger undesirable errors; f.i. my integrated screen stayed black, my external screen was out of sync after updating to xorg-x11-driver-video-radeonhd-1.2.5_20090901_f7ad938-1.1. This is the version shipped by default with OpenSuSE 11.2, Milestone 7. If you are using OpenSuSE 11.1 or 11.0 and feel adventurous then you may install the newest Xorg and radeonhd by the following commmands:
zypper ar http://download.opensuse.org/repositories/X11:/XOrg/openSUSE_11.1/ Xorg-newest
zypper dup -r Xorg-newest
If you experience problems you should report an error at freedesktop.org. You may test without an /etc/X11/xorg.conf or even better with this minimal xorg.conf. Attach your /var/log/Xorg.0.log to the bug report. Basically preconfiguring an xorg.conf by tools like SaX or simply re-using your old xorg.conf should resolve the issue. However this is not the case for the driver version stated above.
The basic rescue action for this driver build or when having OpenSuSE 11.2, Milestone 7 installed is to use framebuffer mode instead of radeonhd by simply copying /etc/X11/xorg.conf.install to /etc/X11/xorg.conf.
However the usage of framebuffer mode will pose a regression since it offers no hardware acceleration and in the current state no xinerama support. That is why you may want to downgrade your radeonhd from Milestone 7 to Milestone 6 so that it becomes usable again. I have created an own x86_64 - xorg-ancient repo for this purpose:
zypper ar http://repos.elstel.com/xorg-anc Xorg-anc
zypper mr -p 20 Xorg-anc
zypper dup -r Xorg-anc
Unfortunately the repo currently only provides packages for the x86_64 architecture. If you still have an i586-image of Milestone 6 residing on your computer please write me a mail to email@example.com so that we can add i586 support
If you should need the downgrade and want to test whether current versions of radeonhd have improved there is a simple way to keep the old working driver in a directory of your choice so that you can update xorg & radeonhd without any hazard: Copy the content of the /usr/lib64/xorg/modules or /usr/lib/xorg/modules to a directory of your choice say /var/tmp/xorg_modules and add the following line to the files-section of your old xorg.conf:
Then your old xorg.conf will always use the old driver and hence work after any kind of update. At me the content of this directory is made up by the following packages: