Comment # 2 on bug 1188954 from Stefan Dirsch

Not sure why you want to enable Sea Islands (CIK)  support in amdgpu kernel
driver. I doubt it gets sufficient testing. 

I suggest to use radeon kernel module (default). Then possibly with "radeon"
DDX, but "modesetting" should be fine as well, then using Mesa driver for
acceleration via Glamor. If this fails as well, we can discuss again.