adding radeon.modeset=0 in /boot/grub/grub.cfg to kernel line before "quiet" did solve my problem. after another kernel update, might have to do it again.
-- [drm:radeon_dvi_detect] *ERROR* HDMI Type A-1: probed a monitor but no|invalid EDID https://bugs.launchpad.net/bugs/539851 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
