[alsa-devel] soc-dsp programming model for loopbacks

Mark Brown broonie at opensource.wolfsonmicro.com
Wed Jan 25 21:14:39 CET 2012

On Wed, Jan 25, 2012 at 12:03:42PM -0800, Pierre-Louis Bossart wrote:
> > That's what the CODEC<->CODEC stuff is all about, hiding the link from
> > userspace.

> I can see how this would simplify the loopback part, but doesn't it make the
> 'regular' playback/capture functionality more complex? If my DSP is seen as
> a CODEC, how do I represent the CPU-DSP interface (DMA or shared memory)?

You'd need a DAI for that interface but you'll need that no matter what
you do, it'll just be a very simple DAI that needs no configuration for
things like AIF format.  With the soc-pcm setup you also need the front
and back end DAIs so it's about the same, the benefit comes at runtime.
My primary focus for the CODEC<->CODEC links is actually things like
basebands rather than on-SoC DSPs, it's just that if the hardware can be
thought of in the same way it should simplify things a little.

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