This issue happens with the i810 driver as well: https://bugs.freedesktop.org/show_bug.cgi?id=8178 I have hacked around the problem by commenting out the using of vbetool in the suspend.d scripts. Perhaps this would work for the radeon driver as well. Anyhow, Alan Hourihane (maintainer of the i810 Xorg driver) suggested that vbetool was the culprit.
-- garbled or no video output after resume from suspend (Inspiron 4150) https://launchpad.net/bugs/31425 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs