https://bugs.freedesktop.org/show_bug.cgi?id=65068
--- Comment #4 from Austin Lund austin.lund@gmail.com --- I'm not sure if this has anything to do with this bug, but the PCI config space is all messed up when running on the integrated GPU:
# cat /sys/kernel/debug/vgaswitcheroo/switch 0:IGD:+:Pwr:0000:00:02.0 1:DIS: :Off:0000:01:00.0 2:DIS-Audio: :Off:0000:01:00.1 # lspci -s 01:00 -xx 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6600M/6700M/7600M Series] (rev ff) 00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Turks/Whistler HDMI Audio [Radeon HD 6000 Series] (rev ff) 00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Maybe this is why suspend/resume doesn't work? Should the apple gmuxer remove the radeon device from the list of pci devices when in this state? (Like hotplugging?)