atombios stuck executing D850 when trying to switch to 4k at 60Hz on Polaris10

[Clemens Eisserer]

Hi there,

I am trying to connect a LG 32UD59 UHD monitor to a MSI Armor RX570 4G
card via a HDMI2 (cheap) certified cable.
Unfourtunatly the setup only runs at 30Hz, whereas when booting
Windows it automatically selects 3840x2160 at 59Hz.

I played a bit with adding the modelines manually, however when
enabling those new modes the screen goes black and in syslog I find
the following entries:

[  571.174813] [drm:atom_op_jump [amdgpu]] *ERROR* atombios stuck in
loop for more than 5secs aborting
[  571.174862] [drm:amdgpu_atom_execute_table_locked [amdgpu]] *ERROR*
atombios stuck executing D850 (len 824, WS 0, PS 0) @ 0xD992
[  571.174908] [drm:amdgpu_atom_execute_table_locked [amdgpu]] *ERROR*
atombios stuck executing D70A (len 326, WS 0, PS 0) @ 0xD7A6

Xorg.0.log: https://pastebin.com/LmZ0bvyL
kernel log: https://pastebin.com/rXGVMTnV

Help would be really appreciated - I am rather latency sensitive and
those 30Hz are driving me nuts ;)

Best regards, Clemens