Re: Re: [PATCH v4 12/23] ASoC: simple-card: Support DPCM DAI link with multiple Codecs

[Sameer Pujar]

On 6/30/2020 4:31 PM, Mark Brown wrote:
> On Tue, Jun 30, 2020 at 01:22:29PM +0530, Sameer Pujar wrote:
>
> > Yes there are complex use cases, but if we look at the amount of changes
> > required in simple-card driver that is not too much. Existing binding for
> > simple-card driver would still work fine for our cases. Yes there are some
> > deviations and we don't want to break existing users, that is why a *new*
> > compatible was introduced and specific items can be pushed under it.
> > Majority of the simple-card driver is getting re-used here. We just need to
> > make sure it does not affect anyone else.
> Why simple-card and not audio-graph-card?

Frankly speaking I have not used audio-graph-card before. I had a brief 
look at the related binding. It seems it can use similar DT properties 
that simple-card uses, although the binding style appears to be 
different. However I am not sure if it offers better solutions to the 
problems I am facing. For example, the ability to connect or form a 
chain of components to realize more complicated use cases with DPCM, 
some of which were discussed in [0]. Can you please help me understand 
why it could be preferred?

[0] https://lkml.org/lkml/2020/4/30/519

> > > Using fe/be instead of cpu/codec is easy to understand.
> > I guess you are referring to DT binding part. The parsing code specifically
> > looks for "codec" sub node and thus present conventions had to be used.
> Remember that this stuff gets fixed into the ABI so we'd have to live
> with this for ever.