Ubuntu, detect new display

ubuntu display multi-monitor gdm

6,146

OK, so you have an HP Elitebook 850 G5, which does not seem to have the optional discrete Radeon R59 GPU installed, and so it's working with just the Intel GPU that's integrated into the processor. So it should be pretty straightforward, with none of the complications of multiple GPUs.

If the HDMI port is listed as "disconnected" in the xrandr output, (e.g. as HDMI-1), then please verify:

the cable is good (i.e. it works with some other computer/display)
the display is powered on and (if applicable) has the correct HDMI input selected
the cable is firmly plugged in at both ends

If xrandr still shows the HDMI display as disconnected, then there might be a hardware problem.

But if it shows the HDMI as connected but disabled, it's waiting for activation. In that case, you would need to do something like xrandr --output HDMI-1 --auto (or the equivalent action in the GUI configuration panel of your desktop environment) to enable it. If working on the command line, you might want to add an option like --left-of eDP-1 to specify the location of the new display relative to the laptop's built-in display, or --same-as eDP-1 if you want the same view on both displays.

6,146

Author by

gervais.b

Updated on September 18, 2022

Comments

gervais.b over 1 year
Running Ubuntu based Os on my Laptop, I have an external HDMI display that is not detected. I tried lspci and xrandr but the display stay "disconnected".

How can I detect the display and extend my desktop ?

Thanks

lspci -d ::0300 -nnk
```
00:02.0 VGA compatible controller [0300]: Intel Corporation UHD Graphics 620 [8086:5917] (rev 07)
        DeviceName: Onboard IGD
        Subsystem: Hewlett-Packard Company UHD Graphics 620 [103c:83b2]

        Kernel driver in use: i915
        Kernel modules: i915
```
lspci -d ::0302 -nnk

No result

sudo dmidecode -s system-product-name
```
HP EliteBook 850 G5
```
- telcoM almost 4 years
  
  Your laptop may have more than one GPU, and the HDMI connector and the internal display may be hardwired to different GPUs. First, please run lspci -d ::0300 -nnk and edit the output into your question. That should tell us which GPU you're currently using, and perhaps if there is another GPU present. Then, please run sudo mount -t debugfs none /sys/kernel/debug to mount a DebugFS virtual filesystem, and then run sudo cat /sys/kernel/debug/vgaswitcheroo/switch: the result should reveal if your system has a way to switch outputs between GPUs. This information will help us help you.
- gervais.b almost 4 years
  
  Mounting the debug fs does not work: mount: /sys/kernel/debug: none already mounted on /sys/fs/bpf. and /sys/fs/bpf is empty. Thanks for your help
- telcoM almost 4 years
  
  Try using any other word in place of none: when mounting a virtual filesystem like debugfs, the device name is not needed and is just a placeholder to satisfy the mount command. Please add information on the exact model of your laptop (the output of sudo dmidecode -s system-product-name would probably be best). Also, the other GPU might use a different PCI class code: you might want to try lspci -d ::0302 -nnk also.
- gervais.b almost 4 years
  
  I tried to mount with other names but still the same result : mount: /sys/kernel/debug: 4578478 already mounted or mount point busy.
- gervais.b almost 4 years
  
  I guess I managed to mount it : mount | grep -i debugfs : debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime) but there are no "vgaswitcheroo" directory in that folder.
- telcoM almost 4 years
  
  Or perhaps it was already mounted by default, which I did not expect... anyway, there are 6 different generations of HP Elitebook 850, and there should be a number after the G at the end of the model name.
- gervais.b almost 4 years
  
  It's a G5, sorry it was not pasted.
- user1660210 almost 3 years
  
  Solution which works for me: 1. suspend computer 2. connect display 3. wake up computer (ubuntu 21.04, wayland, gnome, kernel 5.11)
gervais.b almost 4 years

Thanks a LOT for your support. All ports (except the default "eDP-1") are disconnected. I am working elsewhere today, without external monitors. I will not be able to do it in the GUI because the monitor is not shown, but will try the command as soon as possible and keep you informed.
gervais.b almost 4 years

The issue seems to be with my screen. However some are working and some don't. I got one, smaller than the original one, but who is detected automatically.