I can only tell that you need to have a proper dtb configuration (like here: arch/arm64/boot/dts/amlogic: modify audio_pin1 and usb parameters for… · kszaq/[email protected] · GitHub) and a working audio driver. I'm not sure whether SPDIF works with mainline kernel.
okay so more of a dts problem, good.
by "working audio driver" you mean the correct kernel config (assuming the sources are also there), right ?
# Audio Interface
# Amlogic Audio Interface V2
# CONFIG_AMAUDIO2 is not set <- what's that one ?