USB-C and monitor issue in Ubuntu


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Aug 1, 2018
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I have Ubuntu installed in a Lenovo P1. I want to connect an external screen. I use an USB-C to HDMI converter, but when I plug in the screen, nothing happens. I am only able to select the laptop monitor.

I also tried by connecting it directly via HDMI with no results.

If I issue "dmesg", I can see the log when I plug the USB connector, but that's all.

The same machine with Windows works perfect with a secondary screen.

¿Do I have to enable the USB-C port or do something extra?

Thanks in advance!

I'm suspecting that your display is not identifying itself to the video source, or at least not in a way that Linux / X11 / Wayland expects.

From a few versions ago, HDMI is expected to comply with EDID -- Extended Display Identification Data (check this -- wikipedia usually has good articles that would suggest what to try / what to check / what to read next). When a display sends that to the computer, the desktop environment can recognise the parameters that they can use the display with, like resolution, color depth and frequencies.

Suggestions: if you're using X11, change to Wayland and try again; if you're using Wayland, try X11. Different desktop environments have different strategies and fallbacks, and this includes Windows. Depending on how are they coded, one can be sort of better at guessing than others.

Next, check if your cables and adapters are the same version of HDMI than the display, or higher. Because yes, part of the compliance with the HDMI spec is meant to be in the cable!

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