linux-kernel - Re: [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI links

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Message-ID: <5329E2A6.2040605@ti.com>
Date:	Wed, 19 Mar 2014 20:32:06 +0200
From:	Jyri Sarha <jsarha@...com>
To:	Mark Brown <broonie@...nel.org>
CC:	Jean-Francois Moine <moinejf@...e.fr>,
	<alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
	<linux-kernel@...r.kernel.org>, Xiubo Li <Li.Xiubo@...escale.com>
Subject: Re: [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI
 links

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@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
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