Pinephone/Phosh: Headphone volume is set to zero/mute per default in profile "make a phone call"

Describe your issue

What's the expected behaviour?

I receive a phone call and plug in my headphones/headset. I can hear the person on the other side and this person can hear me.

I think the volume should be set to a fixed reasonable value or the volume level of before rebooting should be restored (this might be related to #936)

What's the current behaviour?

I receive a phone call and plug in my headphones/headset. Volume of the headphones is automatically set to 0/mute. The other person can't hear me and I cannot hear the person.

This bug is rather annoying. First, I haven't thought on the volume level and had the impression that headphones are not working at all.

How to reproduce your issue?

Get a phone call and plug in your headphones/headset.

What device are you using?

Pinephone 1.2b (mobian edition) running the custom firmware by Biktorgj

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• v21.12
• v21.06 (supported until 2022-01-29)

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo (Wayland/Sway)

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm
• Sxmo (Xorg/Dwm)

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)

Don't know. But I have to admit that I have installed the 21.12 version before it was officially released.

Additional information

This issue is not present when listening to music, etc. (normal profile.)

Thank you for all your work on postmarketos! I am using my pinphone for four weeks as my primary phone :)