(In reply to Dmitry from comment #2)
> Almost. The shutdown did not work on 4.16.13 and earlier. And there is now
> on my fresh 4.17.2.

What is there now?

> Disable by removing amdgpu.dc=1 of the string.

DC is enabled by default as of 4.17, you have to explicitly disable it with
amdgpu.dc=0.

> P.S. I noticed that there is a bug and when you disable TearFree in the
> config.

Please file a separate report about that against product xorg, component
Driver/AMDgpu.