[RPi4] Stuck on LibreELEC Screen when Booted through AVR

    Recently reinstalled LibreElec 12.2.1 on RPi4b. When the Pi is plugged directly into the AVR, it gets stuck on the splash screen. It successfully boots when plugged into TV or 1080p/2k/4k monitors. If I boot from monitor and then plug into AVR after, it will load video/audio. If I boot from TV and then plug into AVR, it will not load video/audio. Before the reinstall, the Pi showed video/audio through AVR with no issues.

    Things I have tried:

    - New HDMI cords

    - Disabling CEC

    - Changing LibreElec resolution

    - Clearing Cache

    I have not tried:

    - Modifying config.txt (not sure what I need to add/change)

    - Modifying EDID (no getedid gpu command, so not sure what GPU type I have)


    Debug Logging Files:

    - Boot from TV: https://paste.libreelec.tv/champion-insect.log

    - Boot from AVR: https://paste.libreelec.tv/tidy-coyote.log

    - Boot from Monitor: https://paste.libreelec.tv/rational-chimp.log

    The config.txt file has 4K60 modes enabled so I'll guess that the HDMI port the TV connects to the AVR on only supports 4K60 4:2:0 input so the AVR advertises this to the downstream RPi4 which does not support 4K60 4:2:0 output; so the RPi4 cannot negotiate a valid 4K HDMI mode and Kodi is forced to start 'offscreen' and you see a blank screen instead of the Kodi home screen.

    Switching the HDMI input on the TV to a port that supports 4:2:2 input or changing port properties to allow 4:2:2 input will be the best fix. You can also add video=HDMI-A-1:1920x1080M@60D to kernel boot params in cmdline.txt to force the initial DRM connector state to 1080@60 instead of 4K to get the Kodi home screen showing; but this will not fix the underlying 4K handshaking issue if/when you try to play 4K media.

    NB: This wiki article has some general notes on setup: https://wiki.libreelec.tv/configuration/4k-hdr