[alsa-devel] [RFC][PATCH] ASoC: add simple-graph-card document

[Kuninori Morimoto]

Hi Sylwester

> > Is the main difference between "normal" and DPCM card that in case of the
> > former the data flow routes are static and the latter allows dynamic
> > reconfiguration of sound data routes? AFAIU DPCM stands here for Dynamic
> > PCM [1], rather than Differential Pulse Code Modulation.
> 
> DPCM is a Linux internal abstraction that doesn't represent what's going
> on in a very generic fashion which makes it problematic when it appears
> directly in DT bindings.  It's very SoC centric.
> 
> > It seems the graph based binding could cover above both cases.  Apologies
> > if this has been explained before, but what are main reasons for introducing
> > the graph based binding?
> 
> The simple card is creaking at the seams as it was only really designed
> to represent very simple use cases but has been extended rather beyond
> that.  It's also not set up to cope with things like CODEC<->CODEC links
> that don't involve the CPU as it really only has the idea of point to
> point links between a CPU DAI and a CODEC DAI.
> 
> > Is the SCU part in "ASoC simple SCU Sound Card" derived from "(S)ample Rate
> > (C)onverter (U)nit" ?
> 
> Yes.

The original driver was created for Renesas SCU feature which needed DPCM's
.be_hw_params_fixup() for converting. It was created based on simple card.
At first, it was created as Renesas specific sound card,
but I changed/moved it to one of simple card. Then I named it as simple scu card.

Best regards
---
Kuninori Morimoto