Comment 28 for bug 1211920

need root privige to acces the /dev/snd/hwC*

sudo hda-verb

hda-verb
~~~~~~~~
hda-verb is a tiny program that allows you to access the HD-audio
codec directly. You can execute a raw HD-audio codec verb with this.
This program accesses the hwdep device, thus you need to enable the
kernel config `CONFIG_SND_HDA_HWDEP=y` beforehand.

The hda-verb program takes four arguments: the hwdep device file, the
widget NID, the verb and the parameter. When you access to the codec
on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first
argument, typically. (However, the real path name depends on the
system.)

The second parameter is the widget number-id to access. The third
parameter can be either a hex/digit number or a string corresponding
to a verb. Similarly, the last parameter is the value to write, or
can be a string for the parameter type.