Comment # 8 on bug 66963 from John

Same issue, with 3.11 RC2 and radeon.dpm=1 on a Lenovo T500 with a AMD 3650.
Though my screen goes black and then gradually goes white when enabled. Without
the option pc boots normally.

Graphics: Switchable (disabled) between AMD 3650 and Intel 4500
Linux: 3.11 rc2
OS: Kubuntu 13.04
KDE: 4.11 beta 2
xorg: xorg-edgers ppa enabled