[PATCH RFC v4 3/8] ASoC: hdmi-codec: Add hdmi-codec for external HDMI-encoders

[Russell King - ARM Linux]

On Sat, Sep 19, 2015 at 10:54:51AM -0700, Mark Brown wrote:
> On Fri, Sep 18, 2015 at 02:06:40PM +0300, Jyri Sarha wrote:
> > +#define SPDIF_FORMATS	(SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |\
> > +			 SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_S20_3BE |\
> > +			 SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |\
> > +			 SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE)
> > +
> > +#define I2S_FORMATS	(SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |\
> > +			 SNDRV_PCM_FMTBIT_S18_3LE | SNDRV_PCM_FMTBIT_S18_3BE |\
> > +			 SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_S20_3BE |\
> > +			 SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |\
> > +			 SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |\
> > +			 SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE)
> 
> I'm not sure how abstracted this I2S and S/PDIF DAI business is - it
> doesn't feel like something that's going to be a property of all HDMI
> devices, and the specific sets of formats above cause me to raise a bit
> of an eyebrow.  Should this be an interface where the HDMI chip
> registers multiple interfaces if it has them instead of automatically
> getting this split as is?

The inclusion of the 32-bit formats does raise an eyebrow here too.
Audio transmission across the HDMI link is S/PDIF, supporting up to
24-bit uncompressed audio (aka L-PCM).

The device may accept 32 bit I2S, but it would have to be truncated to
24 bit before transmitting it to the sink.  This should be mentioned
somewhere.

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