[alsa-devel] [PATCH v2] ASoC: rsnd: enable SRC setting via DT

[Mark Brown]

On Tue, Aug 05, 2014 at 01:39:13AM -0700, Kuninori Morimoto wrote:

> Q1
> About DPCM, if my understanding was correct,
> the FE/BE for above feature will be like below.
> Here, CPU (= FE) can covert rate for codec (= BE).
> But, is it correct ? if not, what is the correct connection ?
> 
>      FE:  CPU   <-> dummy
>      BE:  dummy <-> codec

That's right.

> Q2
> This is extra question, but,
> if my understanding was correct,
> DPCM can use "single source (= CPU), multi sink (= codec)" playback ?

It should be able to do any combination of sources and sinks.

> Q3.
> I know Lars-Peter pointed DT idea for DPCM via
>      http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/media/video-interfaces.txt
> 
> and, you and Jean-Francois discussed about it in
>      Subject: Re: [alsa-devel] [PATCH] ASoC: generic: add generic compound card with DT support
>      Date: Thu, 2 Jan 2014 13:44:37 +0100
> 
> But, it seems that there is no final agreement in ML ?

Right.

> In my understanding, FE/BE connection is controlled by amixer,
> this means connection is not statically, but dynamically selected.
> (Or can we use statically linked FE/BE ?)
> I think, we can use above video-interfaces.txt idea for DT,
> but, not 100% good match for us ?
> Can you show me your DT binding idea for DPCM ?
> I can study it, and try to implement it.

This depends a bit on the hardware.  If the audio block is one single IP
to the rest of the system then DPCM probably ought to be totally
transparent to DT and just look like a couple of DAIs attached to the IP
or something.  If the blocks are separate blocks that can be connected
up any old way then it gets a lot more complicated.  How does your
system look?
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