Quick update to this post in the spirit of being a good Internet citizen.
The fix was downgrading from Bookworm to Bullseye (32-bit). The key change that made everything work was switching from the newer vc4-kms-v3d video driver to the older vc4-fkms-v3d overlay. Turns out the full KMS driver, which Bookworm uses by default, just doesn’t play well with ARC or eARC audio on this setup. Note that Bullseye also uses the kms driver, but you can downgrade to fkms by editing /boot/config.txt
I also added hdmi_ignore_cec=1and hdmi_ignore_cec_init=1 to /boot/config.txt to stop the Pi from interfering with the TV’s CEC controls and HDMI ARC handshake. That was it. Just switching to fkms and setting the CEC ignores was enough.
Now the soundbar is not disabled when switching to the Apple TV.
Posting this in case someone else stumbles into the same weird interaction between Raspberry Pi video drivers and HDMI ARC, especially on newer TVs.
The fix was downgrading from Bookworm to Bullseye (32-bit). The key change that made everything work was switching from the newer vc4-kms-v3d video driver to the older vc4-fkms-v3d overlay. Turns out the full KMS driver, which Bookworm uses by default, just doesn’t play well with ARC or eARC audio on this setup. Note that Bullseye also uses the kms driver, but you can downgrade to fkms by editing /boot/config.txt
I also added hdmi_ignore_cec=1and hdmi_ignore_cec_init=1 to /boot/config.txt to stop the Pi from interfering with the TV’s CEC controls and HDMI ARC handshake. That was it. Just switching to fkms and setting the CEC ignores was enough.
Now the soundbar is not disabled when switching to the Apple TV.
Posting this in case someone else stumbles into the same weird interaction between Raspberry Pi video drivers and HDMI ARC, especially on newer TVs.
Statistics: Posted by arbitraryentity — Mon Jul 28, 2025 10:41 pm