Comment # 8 on bug 105760 from taijian@posteo.de

OK, the issue still persists with 4.17rc2. Same as before, I can boot into cli
but trying to start X results in a hung system because X cannot access the
dGPU. 
For reference, my firmware is current as of 

  Qs linux-firmware
  local/linux-firmware 20180402.8c1e439-1