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

[Kuninori Morimoto]

Hi Mark

> > > > >   48kHz   --->      48kHz
> > > > >   44.1kHz ---> [SRC] ---> [codec]
> > > > >   96kHz   --->

I would like to confirm about this again.

> > If yes, and if I want to exchange rate from 96kHz -> 48kHz,
> > I can use be->dai_link->be_hw_params_fixup() for 48kHz settings ?
> 
> That's the idea, yes.

I need to add DPCM support for above sample rate convert feature,
and, I need it under DT.
So, I need to add DPCM DT support as 1st step.
Of course I want to add it on simple-card driver.

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

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

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 ?

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.

Best regards
---
Kuninori Morimoto