(In reply to Bjorn from comment #50)
> That did not help. However, looking closer at my dmesg output on the
> 4.17-wip branch, I see that there's actually some error loading the intel
> graphics firmware. In particular, there are these lines:
> 
> [    1.806186] i915 0000:00:02.0: Direct firmware load for
> i915/kbl_dmc_ver1_04.bin failed with error -2
> [    1.806188] i915 0000:00:02.0: Failed to load DMC firmware
> i915/kbl_dmc_ver1_04.bin. Disabling runtime power management.
> 
> This definitely seems to imply the intel card is having some power
> management issue. So perhaps my problem was never with the AMD GPU at all...
> 

OK, I'm not seeing that at all, and I also have a Kaby Lake chip. What version
of Linux-Firmware are you using?