understanding mixer_paths.xml in android

Question

I am currently learning the audio domain of android OS with qualcomm chipsets. I have come across mixer_paths.xml file. I have been trying to understand the convention of writing and modifying the files. But I am not able to find any proper documentation or guide explaining the convention followed. Can anyone let me know whether there is any such documentation available or else explain in brief the convention followed?

Answer 1

Not the best answer but I think it have something to do with TinyAlsa, the configuration file found in the site is very similar to mixer_paths.xml :

    <!-- TinyHAL configuration file for Nexus S -->
<tinyhal>

 <!-- We are able to have most of our routing static so do that -->
 <path>
   <!-- AIF1->DAC1 -->
   <ctl name="DAC1 Switch" val="1" />
   <ctl name="DAC1L Mixer AIF1.1 Switch" val="1" />
   <ctl name="DAC1R Mixer AIF1.1 Switch" val="1" />

   <!-- DAC1->Headphone -->
   <ctl name="Left Headphone Mux" val="DAC" />
   <ctl name="Right Headphone Mux" val="DAC" />

   <!-- DAC1->Speaker -->
   <ctl name="SPKL DAC1 Switch" val="1" />
   <ctl name="SPKR DAC1 Switch" val="1" />
   <ctl name="SPKL Boost SPKL Switch" val="1" />
   <ctl name="SPKL Boost SPKR Switch" val="1" />
   <ctl name="Speaker Mixer Volume" val="1" />

   ...

</path>
</tinyhal>

http://opensource.wolfsonmicro.com/content/tinyhal