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Today I booted my PC and the resolution of the screen was different to what it was when I turned it off yesterday, so I wanted to used xrandr to change it back, but then I saw this output:

$ xrandr                                                                                                                                                                                                                                                                                                                   
Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 16384 x 16384                                                                                                                                                                                                                                                      
DisplayPort-0 disconnected primary (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected 3840x2160+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
  3840x2160 (0x5a) 533.250MHz +HSync -VSync
        h: width  3840 start 3888 end 3920 total 4000 skew    0 clock 133.31KHz
        v: height 2160 start 2163 end 2168 total 2222           clock  60.00Hz

Notice it says all screens are disconnected, even though I know at least one screen is connected as I'm using it. The screen attached to DisplayPort-2 is the one that should be in use.

I unplugged the cable and plugged it back, and now xrtandr shows the right info:

$ xrandr
Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 16384 x 16384
DisplayPort-0 disconnected primary (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 607mm x 345mm
   3840x2160     60.00*+  30.00    29.97
   2560x1440     59.95
   1920x1200     60.00
   1920x1080     60.00    59.94
   1600x1200     60.00
   1680x1050     59.95
   1600x900      60.00
   1280x1024     75.02    60.02
   1440x900      59.89
   1280x800      59.81
   1152x864      75.00
   1280x720      60.00    59.94
   1024x768      75.03    70.07    60.00
   832x624       74.55
   800x600       72.19    75.00    60.32    56.25
   640x480       75.00    72.81    66.67    60.00    59.94
   720x400       70.08
HDMI-A-0 disconnected (normal left inverted right x axis y axis)

What can cause xrandr to not recognize the screen? And why could my screen resolution had changed out of the blue?

Thanks.

Other info:

  • I'm using Ubuntu 18.04.3 LTS.
  • My video card is a Radeon RX 480
  • uname -r yields 4.15.0-74-generic
DWilches
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  • What video card do you have in your system? What is the output of uname -r? What is the output of dkms status? Please add this to your question. The reason I am asking is that the kernel 5.3.xxxxx version sometimes does not build the NVIDIA driver into the kernel and if you had a recent update there is a possibility that the driver did not build into your kernel. Thank you! – Terrance Jan 29 '20 at 04:50
  • @Terrance I've added the requested information. About dkms, I don't have such program installed, should I? Thanks – DWilches Jan 29 '20 at 05:15
  • No, you don't have to install it. You have a Radeon card, so that throws the NVIDIA driver theory out. Do you know how your driver was installed into your system? My server has a Radeon card in it and I used https://askubuntu.com/a/939693/231142 to setup the drivers for my card and they work great. The only problem is that these drivers update almost daily, but I have never had an issue with them. – Terrance Jan 29 '20 at 05:17
  • I installed the official drivers from AMD's website in 2016. Now that I think of it, I'm not sure the software manager has been updating this driver. I'll try updating to the latest version and see if I can reproduce the issue. Thanks! – DWilches Jan 29 '20 at 05:31

0 Answers0