[PinePhone pmos CE] [headphone] - ALSA volume not maximized causing sound output level to be too low & not configurable from pmos UI's

Describe your issue

When I plug my speakers into the headphone jack on the top of the pinephone the output is so low I can't hear it with my speakers at max volume from more than a few feet away. The root cause was determined to be the headphone volume in ALSA at 24 instead of 100, and no UI's allow control of this.

What's the expected behaviour?

The sound output should match my other devices (roughly) when at 100% output from the PinePhone.
The sound output level should be anywhere from 3 to 10 times louder than it is.

What's the current behaviour?

The sound output level is too low

How to reproduce your issue?

1. From another phone/laptop/browser enabled device, plug in a set of speakers which have a volume function
2. Maximize your device output and use
3. Play a YouTube video from Firefox and set the volume comfortably using the speaker volume knob
4. Plug into the PinePhone
5. Maximize the PinePhone volume sliders
6. Play the same video

The difference is very big

Workaround / Fix

1. $ apk add alsa-utils
2. $ alsamixer
3. Set headphone volume to 100 to allow Pulse audio complete control

Suggested implementation for this ticket

• Initial install should set ALSA volume to 100 to allow Pulseaudio full control
• Sound settings UIs should set ALSA volume to 100 (this could be a gnome settings upstream impact, I believe)

What device are you using?

PinePhone pmos CE

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• stable (v20.05 branch)

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

Additional information

I have not tried on other OSes, I'm hoping this is a software issue and not a hardware fault.