[alsa-devel] Configuring an audio path within ALSA

rashmi narayan rashmi.nyn at gmail.com
Wed Jun 27 14:04:47 CEST 2012

On Wed, Jun 27, 2012 at 10:57 AM, Patrick Lai <plai at codeaurora.org> wrote:

> On 6/26/2012 12:52 AM, rashmi narayan wrote:
>> Thank you Patrick .
>> Currently my codec driver SGTL5000.c has the following audio map
>> static const struct snd_soc_dapm_route audio_map[] = {
>> {"ADC Mux", "LINE_IN", "LINE_IN"},
>> {"ADC Mux", "MIC_IN", "MIC_IN"},
>> {"ADC", NULL, "ADC Mux"},
>> {"DAC Mux", "DAC", "DAC"},
>> {"DAC Mux", "LINE_IN", "LINE_IN"},
>> {"LO", NULL, "DAC"},
>> {"HP", NULL, "DAC Mux"},
>> {"LINE_OUT", NULL, "LO"},
>> {"HP_OUT", NULL, "HP"},
>> };
>> This map does not have a link from ADC to DAC.
>> You mention "After a set of ALSA mixer commands is issued to create a
>> path from one end point to another end point" , how do we issue those
>> commands? to create a link , currently my alsa mixer shows no option for
>> a ADC to DAC select.
> If you have widgets defined matching what you specify in audio_map, you
> should see mixer command i.e "ADC Mux' base on audio map you have
> given. Then you give amixer 'ADC Mux' 'LINE_IN', this would translate
> to writing codec register to have ADC Mux take LINE_IN as input. Audio
> map is defined base on your CODEC topology. I would not be able to
> comment on how to enable CODEC loopback for your CODEC. However,
> the audio map you provided above is kind of fishy. For example,
> shouldn't DAC be sink instead of source
> {"DAC", "DAC", "DAC MUX"} as opposed to {"DAC Mux", "DAC", "DAC"}
  The DAC MUX is a misnomer , it can be thought of as HeadphoneMux where
the inputs are LINE_IN and DAC(arch of SGTL5000).
The datasheet has a DAC select register to choose between ADC and I2S_
IN(I2S In is default) . I don't see that in the map.
 The driver doesn't understand the command * amixer 'ADC Mux' 'LINE_IN' *it
understands amixer control or alsamixer though .
 So is there any other option for the connect source to destination
command... Am I missing something here?

>> -Rashmi
> --
> Sent by an employee of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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