[alsa-devel] [PATCH 0/20] ASoC: rsnd: add Synchronous SRC and U/O error salvage support

[Kuninori Morimoto]

Hi Mark

Thank you for your feedback

> OK, that's more what I thought this was originally.  It sounds like a
> fairly standard ASRC deployment where the goal is to match the rate the
> system wants to play audio at to the rate that the target hardware
> needs.  That's not too different to the telephony cases where the system
> is in one clock domain (possibly at a very different sample rate) and
> the baseband another and definitely the sort of thing that DPCM is
> intended to support.
> 
> This really would be better done with DPCM with the userspace control
> being provided by the driver for the tuner or the machine driver and
> passed through to set the rate of the back end.  Do you think that's
> achieveable (even if it's just a mostly dummy DAI here)?  That way if
> this is used in a system with a CODEC with a real driver on the end of
> the link things should just work.

Can I confirm about this ? This means, we can..

 - add "sampling rate convert" support on DPCM
   (= our "static" sampling rate convert can use it)
 - add "sampling rate convert interface" support for userland on DPCM
   (= our "dynamic" sampling rate convert can use it)

I think this is achieveable.

My concern about this is card driver with DT.
I and Mark talked about it in LinuxCon before, and adding DPCM support with DT
on simple-card is very difficult (= simple-card is not "simple" today...)
So, I will create new sound card driver which includes DPCM DT support for this purpose.
Then, should I create "renesas-sound-card" under sound/soc/sh ?
or can I create "multi-card" (I don't know this is good naming...) under sound/soc/generic ?
If we can select later choice, it will have very limited feature, but simple DPCM support

Best regards
---
Kuninori Morimoto