[amdgpu/displayport] Blackscreen on native resolution

Submitted by Jan Burgmeier

Assigned to Default DRI bug account

Link to original bug (#107823)

Description

Created attachment 141442
dmesg with drm.debug=0x1e log_buf_len=1M

Hi,

there seems to be some monitor/graphics card combination which lead to a black screen.
In my case it is the native (1920x1080) resolution of a NEC EA223WM monitor and a [AMD/ATI] Carrizo (rev 88). Setting any other mode than the native one via xrandr turns the monitor on. Setting it back to the native one results in a black screen.
It seems unrelated to XOrg as there is also a black screen on the terminal and during boot.
I do not see any errors in dmesg or XOrg log

The error does not occur with module parameter dc=0

Environment:
Kernel: 4.19.0-rc2 (git master)
Mesa: 18.1.6
XOrg: 1.20.1
amdgpu-ddx: 18.0.99 (git master)

Attachment 141442, "dmesg with drm.debug=0x1e log_buf_len=1M":
dmesg