I recently started looking at the adding the vc4-kms-v3d overlay and am trying to understand how to get hdmi audio working. This is for a headless device and I am not running pulseaudio, only alsa.
I cannot get hdmi audio to work. I can get audio on the onboard 3.5mm headphone jack and an i2s hat attached, but not the HDMI audio. This is with a recent kernel on aarch64, linux 5.15.23-1. I have not yet tried armv7 to see if it iny different, but am interested in getting the 64 bit version to work.
I have tried all of these outputs and none put any audio out when connected to an HDMI input on my TV
$this->bbcode_second_pass_code('', 'default:CARD=vc4hdmi
vc4-hdmi, MAI PCM i2s-hifi-0
Default Audio Device
sysdefault:CARD=vc4hdmi
vc4-hdmi, MAI PCM i2s-hifi-0
Default Audio Device
front:CARD=vc4hdmi,DEV=0
vc4-hdmi, MAI PCM i2s-hifi-0
Front output / input
iec958:CARD=vc4hdmi,DEV=0
vc4-hdmi, MAI PCM i2s-hifi-0
IEC958 (S/PDIF) Digital Audio Output
usbstream:CARD=vc4hdmi
vc4-hdmi
USB Stream Output')
Keith