Re: [PATCH v3 4/4] dt-bindings: audio-graph-port: add ch-maps property

[Conor Dooley <conor@kernel.org>]

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On Fri, Oct 13, 2023 at 04:41:42PM +0100, Mark Brown wrote:
> On Fri, Oct 13, 2023 at 12:33:34AM +0000, Kuninori Morimoto wrote:
> 
> > > > +      ch-maps:
> > > > +        $ref: /schemas/types.yaml#/definitions/uint32-array
> 
> > > I only got this one patch, so I have no context at all for this change.
> > > Given that, and since I know almost nothing about sound stuff...
> > (snip)
> > > ...I have absolutely no idea how I would populate "ch_maps" correctly.
> > > Please describe (in the binding) what this property actually does
> > > & how to use it. Also, properties use -s not _s.
> 
> > Some Sound want to use multiple connections between CPUs (N) and Codecs (M).
> > Current audio-graph-card2 driver is already supporting 1:N / N:1 / N:N
> > connections, this patch expand it.
> 
> Some of this explanation needs to go into the binding - someone reading
> the binding should really be able to figure out what numbers to put in
> there without looking at the code.

Absolutely :)

> > ch-maps = <0 0 1> means, 
> > 	cpu0 <-> codec0
> > 	cpu1 <-> codec0
> > 	cpu2 <-> codec1

What happens when you want to convey that codec0 & codec1 are both
connected to cpu0 & codec2 is connected to cpu1?
How would that be described in a DT?
Or is that not something anyone would even want to do?

> > Thank you for your help !!
> 
> So probably somthing along the lines of saying "there should be one
> element in the array for each CPU DAI, this should be the CODEC number
> to route to" (that's probably still a bit unclear but roughly that).


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