[RFC v3 7/7] ASoC: hdmi-codec: Add ELD control

[Russell King - ARM Linux]

On Tue, Jan 19, 2016 at 02:47:50PM +0100, Lars-Peter Clausen wrote:
> On 01/12/2016 04:38 PM, Philipp Zabel wrote:
> > Exporting the ELD bytes to userspace allows an application to select
> > an appropriate audio format depending on the current capabilities of
> > the connected HDMI sink device.
> 
> This needs an explanation why this method, which will require explicit
> support in applications, should be used rather than the standard ALSA
> hardware capabilities reporting.

That can be summed up in one line:

ALSA doesn't know about all the different formats for compressed audio.

As far as I'm aware, applications today just lie to ALSA and use the
"16-bit PCM audio" formats (SNDRV_PCM_FORMAT_S16_LE or
SNDRV_PCM_FORMAT_U16_LE) to send compressed audio via ALSA, relying
on the IEC controls to set the channel status data correctly.

Maybe it would be nice to add formats for DTS, DTS-HD, AC3, OBA, etc
to the ALSA format list.

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