RX480 + SME = amdgpu init failed + null dereference

Submitted by Asbjørn Sannes

Assigned to Default DRI bug account

Link to original bug (#104437)

Description

Created attachment 136470
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.

Attachment 136470, "dmesg when not working":
4.14.8-r1-amdgpu-not-working.txt