[alsa-devel] How to correct params_format on DPCM ?

[Mark Brown]

On Mon, Apr 13, 2015 at 04:54:39AM +0000, Kuninori Morimoto wrote:

> If my understanding is correct, the information which userland
> can get is setuped in .open

Yes.

> But, DPCM cases, it cares only cpu information. why it doesn't care codec ?

Like I said before for most systems that do DPCM (and certainly the ones
Liam's been working on) there's a DSP in place which rewrites all the
data between the front end and the back end so the constraints of the
CODEC aren't visible to the application layer.

> I guess DPCM should be...

>  FE.hw = fe_cpu & fe_codec
>  BE.hw = be_cpu & be_codec

Usually there's nothing "CODEC" visible at the front end for these
systems.

> And, if no FE constraint, final image will be

>  hw = FE.hw & BE.hw

Well, BE and CODEC but probably.
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