Created attachment 136470 [details]
dmesg when not working

When upgrading from linux 4.13.x -> 4.14.x the amdgpu failed to come up, often
hanging my desktop computer.

Ending the amdgpg bring up with:
[drm:gfx_v8_0_ring_test_ring [amdgpu]] *ERROR* amdgpu: ring 0 test failed
(scratch(0xC040)=0xCAFEDEAD)
[drm:amdgpu_device_init [amdgpu]] *ERROR* hw_init of IP block <gfx_v8_0> failed
-22
amdgpu 0000:0a:00.0: amdgpu_init failed


After getting some help in #radeon we figured out that the culprit was that I
had enabled SME (which the CPU Ryzen X1800 support).


Got the same error on 4.15-rc6, but with additional null dereference in DC
code.