Sure, attached. AMD staging kernel. I don't know how to tell whether DC=1 is
really enabled, so I did two runs: one with amdgpu.dc=1 as boot parameter and
one with /etc/modprobe.d/ on top of that.

Procedure was the same both times:
- boot
- X login
- switch to console
- sleep, wakeup
- switch to X

The drm/amdgpu lines appear already in the console right after waking up, prior
to switching to X.

This time "only" X crashed (could still move the pointer); at times the
complete machine is dead, no switching to console and and no SSH.

(as a side note: is is normal that waking up on ryzen takes something on the
order of 10-30s? I'm used to split second wakeups on Intel.)

HTH