HDMI TV causes programs to become unresponsive

I’m experiencing a very bizarre issue with my mother’s computer. Her monitor is connected via DVI cable. Yesterday I bought a HDMI cable, to which I connected our older LCD TV by plugging it into a HDMI port on the same video card. The TV was set as a secondary desktop to the right of the normal screen.

Both devices are detected correctly and work in principle. The issue is that when the television is an active display, everything but the mouse cursor freezes (both the monitor and TV desktops). I can keep moving the mouse cursor, and in some cases even keep using some programs… but often times applications simply stop responding to any input.

The only way to recover the system when this happens is to hit Control + Shift + F2 to go into another runlevel, then Control + Shift + F7 to return to the normal session: This makes applications respond again, but a few minutes later the system stops responding to commands once more.

I used Alt + Shift + F12 to disable desktop effects, the compositing is not what’s causing this. Any thoughts on what could possibly cause such an issue? Here are two screenshots, one showing the exact display configuration and one displaying what versions of display software it has… the system language is set to Romanian but hopefully it’s clear what each field refers to.

https://i.imgur.com/zTklBqB.png
https://i.imgur.com/JNmrVFG.png

I can’t help much but for two points:

  1. All HDMI displays I’ve seen to date are named HDMI-0, HDMI-1, etc. HDMI-A is one of the HDMI standards - there’s A, B C and D - but AFAIK it is still the cable to use. I’m curious if someone else has seen this HDMI-A-0 naming.

  2. Hardware problem? I’d try (a) a different cable, (b) a different TV, perhaps more recent, and (c) another HDMI out device.

Not much help, I know.

No worries. Just need to clarify that I can’t get either a new TV, a new video card, or a new cable… financial reasons. The odd thing is that the device is properly detected, the image properly streamed to it, etc… it’s just that when the TV is enabled as an active display, everything will periodically stop responding to mouse clicks or keyboard input and just freeze into place, though the mouse can be moved and the keyboard still responds (toggling NumLock / CapsLock or changing the runlevel).

Loooooong shot: Do you see the same behavior if you start the computer (I understand it’s a desktop) with only the TV connected?

Hard to test that unfortunately, as it’s difficult to get my primary display back when I do this. The TV is in the neighboring room and I have a wired keyboard / mouse: I need to move the mouse, walk to the TV to see how close the pointer is to the button, walk back and move it a little more to the right, etc… already had fun doing exercise that way lol!

How long is the HDMI cable? Cable quality seems to matter more with longer cables.

Just two ideas:

Did you try disabling compositing in settings rather than with hotkey?

Whichever output xrandr deems primary, trying using xrandr to switch primary to the other (purely as test).

I just had Youtube running in Firefox on the secondary Radeon screen for the past two hours without issue.

http://fm.no-ip.com/SS/KDE/mircea202002141930-3840x1200.jpg

Note this TW hasn’t been updated since 5 weeks ago.

Well, without any testing this becomes a theoretical exercise, when it’s usually harder to nail a solution. But you know best, of course. Good luck

HDMI cable is 10 meters long. The connection is most surely HDMI 1.4 as neither the TV nor the cable nor potentially the video card support 2.0 (the TV is so old I was surprised it had a HDMI port when I saw it).

So no one ever experienced something like this? I’m wondering if I can check any logs for a better indication of what might be happening as the issue occurs. Any suggestions on that?

I think mine is something like that, maybe a little less.

I’m wondering if I can check any logs for a better indication of what might be happening as the issue occurs. Any suggestions on that?
Maybe /var/log/Xorg.0.log will say something. ~/.xsession-errors could have something, and maybe journalctl. Try an IceWM session instead of Plasma. It’s already installed by default in most installations. If the layout isn’t right automatically, you can use arandr, which is what you see in my screenshot. If no problem in IceWM, booting some live media with KDE other than TW and asking in a KDE forum are what I would try next .