I had severe problems in getting my Thinkpad with Radeon 9100 graphics card to hibernate. But after some weeks of googling around I found to disable KMS to solve the problem.
To disbale KMS I either used:
boot command: nomodeset or radeon.modeset=0 or a modprobe option like:
/etc/modprobe.d/radeon_KMS.conf with contents:
options radeon modeset=0
I also found some instructions about disabling DRI which did not do the job but I append them for showing blacklisting of modules:
/etc/modprobe.d/DRI.conf with contents blacklist DRI
There might also exist a file called blacklist.conf alternatively which should include: blacklist DRI
depmod -ae
update_initramfs -u -k ‘uname -r’ -v to also disable DRI in initial ramdisk.
reboot and lsmod|grep DRI