HDMI splitters generally rewrite the EDID to cover the subset of modes that all output devices support. How well it does that rewrite varies based on the splitter chip.
Plug in the good display you want to use.sudo pico /boot/firmware/cmdline.txt
Add to the start of that line (do NOT add any carriage returns).The HDMI port should now always get the EDID as if that good display is connected.
If you want to see what a mess your splitter is making of the EDID, you can use "edid-decode /sys/class/drm/card0-HDMI-A-1/edid" to get a full decode. (edid-decode should be installed by default, otherwise you can "sudo apt install edid-decode").
Plug in the good display you want to use.
Code:
sudo cp /sys/class/drm/card0-HDMI-A-1/edid /lib/firmware/edid.binAdd to the start of that line (do NOT add any carriage returns).
Code:
drm.edid_firmware=HDMI-A-1:edid.binIf you want to see what a mess your splitter is making of the EDID, you can use "edid-decode /sys/class/drm/card0-HDMI-A-1/edid" to get a full decode. (edid-decode should be installed by default, otherwise you can "sudo apt install edid-decode").
Statistics: Posted by 6by9 — Tue Feb 04, 2025 6:52 pm