[alsa-devel] Strange findings about the microphone in SigmaTel STAC9221 A1

[Ivan N. Zlatev]

> - Build the latest driver with your pingconfig patch.

Patch, which adds an "intel-imac-20" pinconfig attached.

> - Unload the driver module.
> - Remove /etc/asound.state (or whatever alsactl stores -- the path is
>   depending on distro)
> - Load the module again; at this state, mixers are muted
> - Get the first codec dump here once

initial-codec attached.

> - Unmute the playbacks as usual.  Check playback.
Playback works.

> - Turn on only "Capture Switch".  Don't adjust "Capture Volume" and
>   "Mux Capture Volume" if they are zero.
>   Test recording once here.  Get codec dump again.

Recording doesn't work. Codec diff:

 Node 0x02 [Audio Output] wcaps 0xd0c05: Stereo Amp-Out
   Amp-Out caps: N/A
-  Amp-Out vals:  [0x7f 0x7f]
+  Amp-Out vals:  [0xff 0xff]
   Power: 0x0
 Node 0x03 [Audio Output] wcaps 0xd0c05: Stereo Amp-Out
   Amp-Out caps: N/A
-  Amp-Out vals:  [0x7f 0x7f]
+  Amp-Out vals:  [0xff 0xff]
   Power: 0x0
 Node 0x04 [Audio Output] wcaps 0xd0c05: Stereo Amp-Out
   Amp-Out caps: N/A
-  Amp-Out vals:  [0x7f 0x7f]
+  Amp-Out vals:  [0xff 0xff]
   Power: 0x0
 Node 0x05 [Audio Output] wcaps 0xd0c05: Stereo Amp-Out
   Amp-Out caps: N/A
-  Amp-Out vals:  [0x7f 0x7f]
+  Amp-Out vals:  [0xff 0xff]
   Power: 0x0

> - If not working, try resetting the input source.
>   Test recording.  Get codec dump.

Reseting the input source doesn't result a difference in the codec
info and recording still doesn't work.

> - Raise "Capture Volume".  Test recording, get codec dump.

After this recording works! Woho! :-)

 Node 0x17 [Audio Selector] wcaps 0x300903: Stereo Amp-In
   Amp-In caps: N/A
-  Amp-In vals:  [0x0e 0x0e]
+  Amp-In vals:  [0x00 0x00]
   Connection: 1
      0x12

> - Raise "Mux Capture Volume".  Test recording, get codec dump.

For the sake of the test I have also umuted and increased Mux, which
results the following diff and a non-working recording

 Node 0x12 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
   Amp-Out caps: ofs=0x00, nsteps=0x04, stepsize=0x27, mute=0
-  Amp-Out vals:  [0x04 0x04]
+  Amp-Out vals:  [0x00 0x00]
   Connection: 7
      0x0e 0x15 0x0f 0x0b* 0x0c 0x0d 0x0a


Regards.
-- 
Ivan N. Zlatev

Web: http://www.i-nZ.net
"It's all some kind of whacked out conspiracy."
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