I use this HDMI switch between PC and PS4, it seems that PS4 has no problems at all but PC often struggles to get signal back and no longer appears on screen after the switch. Looks like PC can perfectly switch without issue in the BIOS or when I boot in “nomodeset”, so it should be something Linux related. I’ve also tried with my intel iGPU bypassing my RX580 and the issue persist.
My setup:
EndeavourOS (Arch Linux), KDE Plasma, SDDM, amdgpu, a cheap nobrand HDMI switch with a simple but respectful job to do
Additional notes:
- If I manually unplug the monitor’s hdmi switch and plug it back in it works, maybe something related to power options?
- Maybe I have to load graphics modules earlier at kernel startup? I don’t know if they are already like this by default on recent kernels but it’s a consideration.
- Another hypothesis is that it’s BIOS related, I’ve already tried to set the PCIe GPU as primary. I have disabled secure boot and fast boot to use the distro.
Check the manual of the switch if it simulates a connected monitor for the client.
Some clients are picky when it comes to unplugging monitors or booting without one.
Wayland also seems to do something weird when the monitor is off (I have some applications where the window becomes tiny when turning off the screen).
I have an HDMI switch that starts acting up if the power cable gets loose. Why does the power cable get loose? No idea, but it’s also a cheap nobrand switch. This probably isn’t your issue, but try pushing the barrel connector in more or try a power supply that supports a higher current (same output voltage). I only mention it because I only managed to “fix” my switch by noticing it was just a mm out of the jack.
Fwiw this would happen to me with 2 windows machines and a KVM switch if I left the monitor connected to the primary machine for too long. Switching back to machine 2 gave no signal. Also same thing with a Linux nuc. It may just be how the output swap is handled on the switch, the monitor might not see it happen.
Have you tried SSH-ing into the system when it’s in the bad state to see if you can diagnose the problem? You might be able to see if any displays are being detected at all in the problematic state. Part of me wonders, though is not certain, if the switch is somehow providing an inconsistent display name that confuses the system, though this is just a hunch - I have no idea what I’m talking about, to be frank.
Also, try switching TTYs and seeing if those show up.
If I change tty I still don’t get the image, the only way is to reboot or manually reconnect the HDMI cable of the monitor.
It’s probably signaling / driver device management related. The HDMI switch will often appear to change display properties to the connected devices, which may confuse them
