[alsa-devel] [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI links

[Jyri Sarha]

On 03/19/2014 03:46 PM, Mark Brown wrote:
> On Wed, Mar 19, 2014 at 12:08:55PM +0200, Jyri Sarha wrote:
>
>> While we are at it we could update the bitclock-master and frame-master
>> syntax to be like this:
>
>> bitclock-master = "cpu"
>> frame-master = "codec"
>
>> With the above explicit definition all the daifmt settings could be defined
>> in link level. For backwards compatibility we could still define that
>> omitting the value equals "codec" and omitting the property equals "cpu".
>
> It seems it'd be a bit more idiomatic to do that with a phandle rather
> than with a string in order to allow extensions for things like TDM (the
> I2S to mono speaker driver use case for example).
>

You mean a like this:

sound {
     compatible = "simple-audio-card";
     simple-audio-card,name = "Simple Audio";
     simple-audio-card,widgets = ...
     simple-audio-card,routing = ...

     simple-audio-card,dai-link at 0 {        /* I2S - codec */
         format = "i2s";
         bitclock-master = <&codec 0>
         frame-master = <&codec 0>;
         bitclock-inversion = <1>;
         simple-audio-card,cpu {
             sound-dai = <&audio1 0>;
             bitclock-inversion = <0>;
         };
         simple-audio-card,codec {
             sound-dai = <&codec 0>;
             system-clock-frequency = <12000000>;
         };
     };
...

Yep, that makes sense when considering tdm setups with multiple codecs 
on the same wires.

Best regards,
Jyri