[alsa-devel] [PATCH v9 1/4] drm/i2c: tda998x: Add DT support for audio

[Jean-Francois Moine]

On Thu, 8 Jan 2015 16:53:41 +0200
Jyri Sarha <jsarha at ti.com> wrote:

> > +  - audio-ports: must contain one or two values selecting the source
> > +	in the audio port.
> > +	The source type is given by the corresponding entry in
> > +	the audio-port-names property.
> > +  
> 
> This binding does not allow multi channel i2s setups with multiple i2s 
> pins. It would be nice to support that in the DT binding, even if the 
> code is not yet ready for it.
> 
> How about having these two optional properties instead of audio-ports 
> and audio-port-names:
> 
> audio-port-i2s: Upto 4 values for selecting pins for i2s port
> audio-port-spdif: Value for selecting input pin for spdif port
> 
> Presence of one of the properties would be mandatory and both are allowed.
> 
> Sorry to notice this only now, but I have not yet looked the drm side 
> changes too closely.

From Andrew's datasheet, the TDA998x's which are handled by the tda998x
driver have only 4 input audio pins, the first two ones being either
S/PDIF or I2s, the last ones being I2S only.

So, the DT description could be reduced to a simple list indexed by
the pin number (= DAI number) and defining the protocol type.

Examples:

- for the Cubox:

	audio-inputs = "i2s", "spdif";

- for some other board with I2S on the pins 3 and 4 only:

	audio-inputs = "none", "none", "i2s", "i2s";

- for a fully wired TDA9983B (no driver yet):

	audio-inputs = "i2s", "i2s", "i2s", "i2s", "spdif";

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