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

[Kuninori Morimoto]

Hi Mark

Thank you for your feedback

> > 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?

I guess our IP is one of complicated system.
Our system have many IP blocks which are called as SSI/SRC/CMD/DVC.
So, in perfect world, I guess it will be

    FE : SSI <-> dummy
    BE : SRC <-> CMD
    BE : DVC <-> codec
    
Or something like that,
but, it is very complicate system at this point.
I think we need 3 or 4 step for it.

Fortunately (?) these blocks are controlled
in rsnd driver as 1 CPU today.
So, I can say we can use it as

    FE : CPU(*) <-> dummy
    BE : dummy  <-> codec

   (*) CPU includes SSI/SRC/CMD/DVC in rsnd driver

This is simple enough and good 1st step for DPCM support.
I think our IP block needed these step

   1. simple DPCM support on DT
   2. sampling rate convert support on DPCM
   3. multi FE/BE support on DT
   4. rsnd multi block IP use multi DPCM

or (1 + 3) -> 2 -> 4 order
How about this plan ?