For me;

Oct 25 15:34:51 phat kernel: fbcon: amdgpudrmfb (fb0) is primary device
Oct 25 15:34:51 phat kernel: amdgpu: [powerplay]
                              failed to send message 148 ret is 0
Oct 25 15:34:51 phat kernel: amdgpu: [powerplay]
                              last message was failed ret is 0
Oct 25 15:34:51 phat kernel: amdgpu: [powerplay]
                              failed to send message 145 ret is 0
Oct 25 15:34:51 phat kernel: amdgpu: [powerplay]
                              last message was failed ret is 0

This was with linux-firmware-20181001. Have also tried
linux-firmware-20181026, which has Tonga updates, but similar blank screen
(didnt check logs). Judging by search hits on the messages it may be a
kernel regression.

Is this combination working for anyone?