AMD RX570 - black screen after powering the screen after Xserver booted with DisplayPort
If I power on my desktop PC with the connected but powered off DisplayPort connected monitor (Dell U2717D), the display won't show the picture if I turn it on. I have to reboot my computer to get the screen to show a picture.
Alternatively, switching the Linux console (Ctrl-Alt-F2), then waiting a minute will make the console text/login prompt appear. Then I can login and restart the display manager (restarting the X server with it) and the X will work normally.
OS is: Arch Linux, Linux 5.12.6-arch1-1 xf86-video-amdgpu-git 539.aedbf47-1
I also tested with xf86-video-amdgpu 19.1.0-2 and other various older versions of the xf86-video driver and the kernel, and afaik this bug has always existed.
I'm not sure if this is technically a kernel/modesetting bug of xf86-video bug.