normally, the pi interrogates the monitor to determine the resolution to set as part of the boot process.
if that pi is not set on the HDMI switch, it will not get a response. i think it will set no display.
however, you might try forcing a display setting on your PI4s.
in /boot/firmware/cmdline.txt (add to the front/end of the line, NOT a new line)
video=HDMI-A-1:1024x768@60D
(or whatever resolution you want)
another note: the KMS driver ignores all video settings in config.txt - video mode changes made to this file will have no effect !
(see this: https://www.raspberrypi.com/documentati ... splay-mode)
if that pi is not set on the HDMI switch, it will not get a response. i think it will set no display.
however, you might try forcing a display setting on your PI4s.
in /boot/firmware/cmdline.txt (add to the front/end of the line, NOT a new line)
video=HDMI-A-1:1024x768@60D
(or whatever resolution you want)
another note: the KMS driver ignores all video settings in config.txt - video mode changes made to this file will have no effect !
(see this: https://www.raspberrypi.com/documentati ... splay-mode)
Statistics: Posted by terribleted — Tue Dec 23, 2025 4:14 pm