External HDMI display shows suddenly as <Unknown> <Unknown>

when connecting my HDMI/TV it stays black, the TV tells me “no signal”.
checking the Settings App shows an unknown display.
wlr-randr outputs the same:

purism@pureos:~$ wlr-randr
DSI-1 “<Unknown> <Unknown> (DSI-1)”
Physical size: 65x130 mm
Enabled: yes
720x1440 px, 63.414001 Hz (preferred, current)
Position: 0,0
Transform: normal
Scale: 2.000000
DP-1 “<Unknown> <Unknown> (DP-1)”
Enabled: yes
848x480 px, 60.000000 Hz
800x600 px, 56.250000 Hz
800x600 px, 60.317001 Hz
1024x768 px, 60.004002 Hz
640x480 px, 59.939999 Hz (preferred, current)
Position: 360,0
Transform: normal
Scale: 1.000000

it used to work and the TV was recognized as Phillips Consumer TV xyz…
How to get my TV over HDMI back working?

i flashed the device and started from scratch!
so, issue is fixed :slight_smile:

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You’ll note that your internal (built-in) display is also “Unknown” - and it’s the same on my phone.

So maybe the problem is the “black” / “no signal”.

got it again. external display/TV not working.
this is how it looks like in Settings App:

#screenshot taken with App from librem5-goodies

instead of “Unknown Unknown” there should be Phillips Consumer TV .

somebody knows a fix for this?

the fix was to unplug and re-plug usb-c.
external display is back but without sound!

i am going to flash the phone.

Any investigation would require to know what hardware, if any, is between your phone and your monitor.

Aren’t you showing us the Built-in display though in that screen shot? Can you use the pull down menu to change to the secondary display or is there no secondary display available in the menu?

I think that might be a known problem (limitation, at this stage).

Regardless, on any Linux computer that I have used, a working HDMI connection at best adds a sound output device and you can choose whether sound will output via HDMI or via a number of other existing choices. (For example, even though HDMI is always capable of carrying audio, the actual video output device may not have any means of outputting audio e.g. no built-in speakers and/or e.g. no attached speakers.)

it’s a USB-C Nano Dock Station (C31NANODOCKLANPD)
you can find it also here:

Tested Accessories · Wiki · Librem5 / Librem 5 Community Wiki · GitLab

screenshot shows the Librem5 screen since TV wasn’t working.
there is no pull-down menu to change displays.
this is how it looks like when it’s working

my TV is recognized/identified with proper name, resolution and refresh rate.

HDMI sound came with an update from about 4 weeks ago, i guess.
As long as the TV is recognized properly i can select HDMI as sound sink in Settings/Sound.

but, from time to time when i plugin the TV into the HDMI port of the hub it does not work.
TV stays black, no desktop; Settings identifies the TV as unknown/unknown with wrong resolution(one my TV can not render) and refresh rate.

in this situation i re-plug the hub, re-plug hdmi and/or reboot the phone.
if all of this does not work i re-flash phone!

I guess it is defaulting to VGA resolution. I am a little surprised that the TV can’t handle VGA (which is supposed to be the emergency fallback when higher resolutions don’t work) but then a TV is not designed to be a computer monitor (and to be fair VGA is now embarrassingly old).

There are a couple of packages around that allow you to debug EDID to see whether there is some confusion with that happening, but I don’t know whether those packages work via a dock.

It may also be a good idea to check the system log for the time at which you plugged in the TV.

I would probably replug the TV into the HDMI connector of the hub in the first instance if things aren’t working. Reflashing the phone seems a bit extreme and not a really viable ongoing solution.