https://bugzilla.kernel.org/show_bug.cgi?id=200633
--- Comment #2 from syboxez@gmail.com --- dmesg: https://ghostbin.com/paste/7pyty Xorg: https://ghostbin.com/paste/38zyy
amdgpu.dc=0 does indeed make the issue go away, so I'm guessing DC was turned on by default for Tonga in this kernel.