Created attachment 142062 [details]
kernel config

System shuts down after reboot command or Ctrl-Alt_Del but fails to actually
reboot. The last line output to the Virtual Console is "Rebooting". The screen
then turns off as normal, but fails to turn on again with the boot menu.
Bisection finds this problem is introduced by commit
0a1d56599b9bb58464a8bf1243191eb32b36b694 which patches
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
Hardware: as documented in Bug 108139