https://bugs.freedesktop.org/show_bug.cgi?id=94708
--- Comment #7 from Marko Tikvic markotikvic@gmail.com --- I added radeon.runpm=0 line to the /etc/default/grub and after running update-grub (as sudo) I got this error /usr/sbin/grub-mkconfig: 35: /etc/default/grub: radeon.runpm=0: not found