I recently updated my laptop to Ubuntu 18.04 from 16.04. When I tried to use my external monitor with it for the first time, everything worked well and I set the external monitor as the primary display. However, for the second time I tried to use my laptop with it, the external monitor only shows a black screen, even though it shows the connected source (it displays a text saying "HDMI", since I connect the monitor via HDMI). Since the laptop recognizes it and the setting was not modified since the last time I used it, the built-in screen is turned off.
When the external monitor is connected, xrandr produces the following output (note that I could only run it "blindly", since both the screens are black whenever the second monitor is connected):
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
LVDS-1 connected (normal left inverted right x axis y axis)
1366x768 60.01 +
1360x768 59.80 59.96
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
1920x1080 60.00*+ 50.00 59.94
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.90
1280x800 59.91
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x480 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DP-1 disconnected (normal left inverted right x axis y axis)
I tried the following things, to no avail:
- add
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amdgpu.dc=0"to/etc/default/grub(see this answer) - change the driver, currently I have:
- install a new nvidia driver, this caused login loop so I had to completely revert this
- "restart" the external screen by running the script shown here
- run
xrandr --output HDMI-1 --mode 1920x1080 --rate 60as described here
