Xfce Forum

derekge

Member

Registered: 2008-04-11

Posts: 8

HDMI signal lost after switching back and forth via a kvm switch

Raspberry Pi OS Lite with a clean install of XFCE and goodies.  All display configurations are default.  I have a hardware kvm switch with a button and sometimes when I switch back to the Pi, the monitor says it can't find an HDMI signal.  I turn off the Pi with it's hardware power switch, unplug the HDMI cable, plug it back in, and power on - this is what brings it back up (cold boot).

After some investigating, it seems that when the Pi's HDMI is not active in the kvm, something somewhere tells the Pi to stop outputting signal to the HDMI.  I'm not sure what log entry I'm looking for (in /var/log/Xorg.0.log?) or if there is another log too look at.

The original OS installed on this same hardware was Raspberry Pi 4 OS desktop with Pixel using a different micro SD card and it never gave me issues when using the kvm switch.

How can I pinpoint the issue further?  I am currently testing logging out each time before I switch away from the Pi to check stability (one forum said this was a workaround).

Thanks!

derekge

Member

Registered: 2008-04-11

Posts: 8

Re: HDMI signal lost after switching back and forth via a kvm switch

Early indications show I have resolved the issue.  What I have done is edit this file:

sudo nano /boot/config.txt

and uncommented out this line:

# Uncomment this to enable HDMI hotplug signal detection.
#hdmi_force_hotplug=1