Pinephone: microphone not working sometimes (hardware issue)

Describe your issue

What's the expected behaviour?

The microphone works for taking voice memos and in phone calls.

What's the current behaviour?

Voice memos record silence/static, and in phone calls, the other person hears nothing, or hears light static if the charging cable is plugged in.

How to reproduce your issue?

Use a pinephone and be on edge on or after June 2. (the 20220602-1926-postmarketOS-edge-sxmo-de-sway-1.9.0-pine64-pinephone.img.xz image has this problem)

• receive a voice call
• Talk into the pinephone
• Verify that you can't hear anything on the other end
• Use DTMF tones on the pinephone
• Verify that you can hear the DTMF tones

or

• Go to menu => Scripts => Record => Microphone
• Talk a little bit while the window is open and "recording"
• Press Control-C (either on the keyboard or through the terminal menu)
• save recording
• open terminal window
• mpv ~/.local/share/sxmo/recordings/2206*.wav
• You hear nothing

What device are you using?

pine64-pinephone

On what postmarketOS version did you encounter the issue?

• edge (master branch)

• v21.12

• v22.06

• I confirm that the issue still is present after running sudo apk upgrade -a

On what environment did you encounter the issue?

Phone environments

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

Other

• No environment ("none" in pmbootstrap)
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm
• Sxmo (Xorg/Dwm)
• console UI
• framebufferphone

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)

2022-06-02

Additional information

As a workaround, the headset microphone works (though it's a little quiet for the person on the other end).

Related: #1552 (closed)