https://bugs.freedesktop.org/show_bug.cgi?id=76490
--- Comment #88 from Tobias Droste tdroste@gmx.de --- Doesn't fix it for me, it still locks up at boot with dpm enabled and the quirk removed.
[drm] initializing kernel modesetting (PITCAIRN 0x1002:0x6810 0x174B:0xE271 0x00)