Comment # 22 on bug 1197434 from Pablo Sanchez

Hi, 

Unfortunately, the mic has stopped working. 

It turns out that it works only after the first boot when the previous
recipe[1] is applied.  After the second boot, it stops working.

Shortly I'll attached some preliminary forensics:  alsa-info.txt and output
from 'alsactl store'.

One key observation is after the first boot (when the mic works),
/var/lib/alsa/asound.state is empty (zero-length).  

After the second boot, the file has content.

::: Recipe  :::
cd /var/lib/alsa

mv asound.state ~

fuser -k /dev/snd/*

# Remove parent device
/sbin/modprobe -r snd_sof_pci_intel_cnl

mod=$(grep -m1 -E '^(snd[^ ]*|ac97_bus) [0-9]+ 0' /proc/modules)
while [ -n "$mod" ]; do
    mod=${mod%% *}
    /sbin/modprobe -r $mod
    mod=$(grep -m1 -E '^(snd[^ ]*|ac97_bus) [0-9]+ 0' /proc/modules)
done

rmdir card0.conf.d

# Should be empty
ls /var/lib/alsa

# confirm no cards listed
cat /proc/asound/cards

reboot