Well, you could try to use the radeonfb module instead the radeon module. There are two ways to do that. First is to leave X, use rmmod to unload radeon, if you get message "driver in use", you'll have to check with lsmod which drivers use radeon and unload them at first. Afterwards you may use
in order to load radeonfb.
If this doesn't work, you may blacklist the "radeon" module and reboot the system. Look at the dokumentation of your distribution about blacklisting.
If this doesn't work as well, you'll have to go to the downloadsite of the vendor of your laptop (referring to the downloadsite of AMD/ATI) and look for the driver.