I am trying without luck to get Ubuntu 20.04 to utilize both of these monitors connected via a single RX-580 graphics card. Here is the output of xrandr -q
xrandr -q
Screen 0: minimum 320 x 200, current 5120 x 2880, maximum 16384 x 16384
DisplayPort-0 connected 2560x2880+2560+0 (normal left inverted right x axis y axis) 600mm x 340mm
2560x2880 60.00*
DisplayPort-1 connected primary 2560x2880+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
1024x768 60.00 +
3840x2160 60.00 +
2560x2880 60.00*
3200x1800 60.00
2560x1440 60.00
1920x1200 60.00
1920x1080 60.00
1600x1200 60.00
1680x1050 60.00
1280x1024 60.00
1440x900 60.00
1280x800 60.00
1280x720 60.00
800x600 60.00
640x480 59.94
HDMI-A-0 connected (normal left inverted right x axis y axis)
1024x768 75.03 + 60.00
1920x1200 59.95 +
1920x1080 60.00 59.94
1600x1200 60.00
1680x1050 59.95
1280x1024 75.02 60.02
1440x900 59.95
1280x800 59.95
1152x864 75.00
1280x720 60.00 59.94
800x600 75.00 60.32
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
HDMI-A-1 disconnected (normal left inverted right x axis y axis)
DVI-D-0 disconnected (normal left inverted right x axis y axis)
I have tried setting up the framebuffer via xrandr --fb 7040x2800 which should be exactly 5120 + 1920 x 2880. The LG Ultrafine monitor is actually two monitors in one and this seems to be the issue. I can't seem to set up the screen size to utilize all three outputs (DisplayPort-1, DisplayPort-0 and HDMI-A-0) at the same time.
I installed arandr and it gives me the following in a .sh file:
#!/bin/sh xrandr --output DisplayPort-0 --mode 2560x2880 --pos 2560x0 --rotate normal --output DisplayPort-1 --primary --mode 2560x2880 --pos 0x0 --rotate normal --output HDMI-A-0 --mode 1920x1200 --pos 5120x0 --rotate normal --output HDMI-A-1 --off --output DVI-D-0 --off
When I run that it flashes the screen but eventually goes back to the LG montior.
What is interesting is that on boot, both monitors are on and at proper resolution. It's only when I log in that I can only use the LG monitor and nothing I try lets me use the HDMI-connected Dell monitor.
Am I asking too much of the xrandr protocol or maybe the ATI video driver?
Any help would be appreciated.
