Inexplicable mixer control creation

[Randy Cushman <rcushman_linux@earthlink.net>]

In attempting to implement my proposed mixer control name changes (see 
"[Alsa-devel] RFC: Enhance AD AC '97 mixer control names") I have 
encountered behavior that makes no sense to me:  If module 
snd_ac97_codec does not create a control with the name 'PCM Playback 
Volume' then something else creates a control with that name.  Not 
surprisingly, this phantom control serves no useful purpose in my 
environment, as it has no affect on AC '97 control registers.

Configuration details:  Using Fedora Core 5 kernel 2.6.18-1.2239.fc5 
(i686) with the latest ALSA-driver source from Mercurial.

Details:
- I have ruled out the possibility that module snd_ac97_codec or 
snd_intel8x0 could be creating the control, because the following steps 
cause the control to disappear:
# modprobe -r snd_intel8x0
# modprobe -r snd_ac97_codec
# modprobe snd_ac97_codec
# modprobe snd_intel8x0
- I have also ruled out (using calls to printk) the possibility of the 
control being created via calls to snd_ac97_cnew(), 
snd_ac97_cmute_new_stereo() or snd_ac97_cvol_new().
- The phantom control appears after booting to runlevel 3 or 5.
- If removed using the above modprobe commands, the phantom control will 
appear after logging into a KDE session.
- If removed using the above modprobe commands, the phantom control does 
not appear after logging into a Gnome session.

Any suggestions for how I might track down the source of this phantom 
control would be welcome.

Randy Cushman



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