[alsa-devel] Feasibility of adding alternative audio transport besides I2S/PWM/SPDIF, etc

[Mark Brown]

On Tue, Oct 13, 2015 at 10:57:45AM +0100, Liam Girdwood wrote:
> On Fri, 2015-10-09 at 09:11 -0700, Caleb Crome wrote:

> > Sorry, I wasn't clear.  The point is to use the 'generic' SPI API in
> > the linux kernel to stream the data, and *not* use an audio format.
> > So, the idea is, the external micro would buffer up a block of data,
> > (in our case, maybe 160 samples * 32 channels  = 10 kBytes), then use
> > the SPI port to read and write to the micro as if it were a memory or
> > something like that to transfer the data.  So the external micro would
> > appear to the CPU as an external register bank, and would do all the
> > audio aggregation.

> Ok, so this sounds like a burst based DAI where the host sends audio
> data in bursts then sleeps. I think this has been done by some codec
> vendors, but I dont know if any code is upstream.

Well, it's not triggerd from the CODEC side which is a bit different to
what the CODEC vendors were trying - it sounds more like what some of
the DSP vendors are doing with bursting data into the DSP over a message
based interface which maps pretty well onto the existing copy()
operation.
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