https://bugs.freedesktop.org/show_bug.cgi?id=63599
--- Comment #35 from Alex Deucher agd5f@yahoo.com --- Created attachment 91154 --> https://bugs.freedesktop.org/attachment.cgi?id=91154&action=edit possible fix
(In reply to comment #34)
$ lspci -nn | grep 'VGA' 00:01.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Sumo [Radeon HD 6480G] [1002:9649]
[ 188.599127] [drm] initializing kernel modesetting (SUMO 0x1002:0x9649 0x17AA:0x21EA).
Thus, is's SUMO isn't it? Should I try to use "max_hw_contexts = 4" for the SUMO case or that's unreasonable?
Your chip was misclassified. The attached patch should fix it.