Still a problem with kernel 4.18.5 and latest firmware for Vega (20180825).

Except now, the session doesn't crash but just hangs with black screen.

Similar dmesg can be seen:

[  162.743804] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us *
3500 tries - dce_mi_free_dmif line:636
[  162.743830] WARNING: CPU: 6 PID: 1575 at
/build/linux-ETX4PU/linux-4.18.5/drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254
generic_reg_wait+0xe8/0x160 [amdgpu]