[RFC] sound: ASoC: multiple DAIs/codecs on single audio stream

[Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>]

Hi,

I am rewriting Marvell Kirkwood/Dove audio driver and I am having
a hard time to match the controllers features to ASoC API.

The controller has a dma controller for one playback buffer. It can
play the stream to both I2S and SPDIF interfaces with independent mute.

Now, for example, I have a board with i2s codec and spdif tx diode
connected to the above controller:

DMA (platform) -+-> I2S (dai) ----> I2S_Codec (codec)
                 |
                 +-> SPDIF (dai) --> SPDIF_TX (codec)

Is there any way in the current ASoC API to have the above setup?

I tried to attach two codecs to a single DAI and that will already
create two playback streams with two buffers. I guess it will also
happen if I have two DAIs connected to the same platform driver?

For an API for SoC audio, shouldn't there be some relation between
platform, DAI, and codec, e.g.:
- a platform represents a single audio stream buffer
- a platform can be attached to one or more DAIs,
- a DAI can be attached to one codec only

Regards,
   Sebastian