WIP: Pinephone calling with audio

This patchset is well just as work in progress,

Steps to get this working,

• Create image with this and additional packages, alsa-utils, pulseaudio-utils, py-dbus, picocom
• I used plasma-mobile as user interface

Booting image should print in dmesg,

[ 10.631685] asoc-simple-card sound-modem: ec25 <-> 1c22000.i2s mapping ok in dmesg

And aplay -L should list the devices,

Next step is enable modem, so it picks up network and ready to call.

One small adjustment which needs to be done is switching audio format using AT commands

sudo picocom /dev/ttyUSB2
AT+QDAI=1,1,0,4,0
AT+QRXGAIN=128
ctrl-a ctrl-q

Once this is done, you can make a call.

Outbound audio (from device to network)

pactl load-module module-loopback source=alsa_input.platform-sound.stereo-fallback sink=alsa_output.platform-sound-modem.mono-fallback

This seems to work normally, and otherside can hear us perfectly

Inbound audio

pactl load-module module-loopback source=alsa_input.platform-sound-modem.mono-fallback sink=alsa_output.platform-sound.stereo-fallback

This doesn't work and gives crap quality audio.