[Doc] Raspberry Pi 4: Sound setup with linux-aarch64

[anarki]

Raspberry Pi4 did not output sound on a default installation of archlinuxarm with default linux-aarch64.

[b]Symptoms[/b]

As root:
- installed alsa alsa-utils pipewire pipewire-audio pipewire-pulse pipewire-alsa wireplumber
- aplay -L listed sysdefault:CARD=Headphones
- speaker-test -D sysdefault:Headphones -c 2 did output test signal
- snd_bcm2835.enable_headphones=1 present in /boot/config.txt had no effect

As user in group audio:
- aplay -L listed sysdefault:CARD=headphones
- speaker-test -D sysdefault:headphones -c 2 worked
- pactl shot list sinks had dummy output only: that was the real issue here

As user not in group audio:
- aplay -L did not list any device
- speaker-test did not work
- pactl shot list sinks had dummy output only: that was the real issue here

[b]Steps to solve it after a fresh installation[/b]

As root:
- install alsa alsa-utils pipewire pipewire-audio pipewire-pulse pipewire-alsa wireplumber pulsemixer uboot-tools
- append snd_bcm2835.enable_headphones=1 to line setenv bootargs [...] in /boot/boot.txt
- run /boot/mkscr (needs uboot-tools)
- reboot
- check /proc/cmdline for snd_bcm2835.enable_headphones=1
- set /boot/config.txt to only: enable_uart=1

As user not in group audio:
- run pactl list short sinks to make sure bcm2835 output is listed
- aplay -L will still be empty
- run speaker-test to ensure test sound is played
- run pulsemixer to ensure built in analog stereo is listed

[graysky]

Not sure about linux-aarch64 have you tried with linux-rpi?

[darksky]

Have you tried hdmi_drive=2 in config.txt

[anarki]

Thank you, graysky. Indeed I did and of course, sound worked out of the box.

Although I prefer to keep setup simple and I find dtoverlay configuration rather confusing. Since that Pi serves as an audio relay only, there is no need for h/w acceleration.