three monitor setup hangs
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| xserver-xorg-video-amdgpu (Ubuntu) |
New
|
Undecided
|
Unassigned | ||
Bug Description
I have a Ubuntu 20.04 setup with three almost identical monitors (1920x1080) connected to a Radeon RX5500XT 8GB. All works fine as long as I don't turn one of the monitors off and back on.
Whenever that happens, all other monitors briefly go blank and then turn back on, as if they are being detected again, and all what I see then is three black screens, with a mouse cursor that still can be moved across all screens. From that moment on, nothing can be done anymore, and I have to hit the reset button of the desktop PC.
The monitors have VGA, HDMI and DVI ports. I tried connected them to the RX5500XT (which has 3xDP+1xHDMI ports), using all possible different combinations of cables. (DVItoHDMI, DVItoDP, HDMItoHDMI, HDMItoDP). The problem persists in any case.
Whenever I start the system with only two monitors connected, there is no problem. If I switch off one of the monitors and back on, I see the other go blank for a second or two, it turns back on, and the canvas is properly filled with menu and background without any issue.
Obviously there is also no problem with only one monitor connected.
I experienced this problem with the standard Ubuntu 20.04 amdgpu driver. So, I tried to install the most recent driver from AMD's website, and that driver has the same issue.
I tried both gdm3 and lightdm. Same problem.
