Created attachment 143781 [details]
Bisect log & result

I have two monitors daisy chained via Displayport 1.2.

GPU: Radeon RX 570 4GB
amdgpu.dc=1 (issue does not occur when disabled)

After upgrading to Linux 5.1-rc1 when switching to a tty the second monitor
(that's connected to the first) displays a corrupted version of the first
monitor. Previously this would display a stretched version of monitor 1
(because of a different aspect ratio).

There is no output in dmesg when switching to a tty.

I have bisected the issue between tags v5.0 and v5.1-rc1. The result was
bc7f670ee04cd619f8c4627c37d77b3618bc5edd as the first bad commit. Bisect log
attached.

commit 8a48b44cd00f10e83f573b9028d11bd90a36de26
GOOD

commit bc7f670ee04cd619f8c4627c37d77b3618bc5edd
BAD
After switching from graphical environment to a tty, the second monitor will
keep displaying the last frame of the graphical environment.

commit b2e85302494a6b7d3a3006c8d80a729377600628
BAD
Screen display is corrupted.