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

From: Mark Brown
Date: Wed Jan 14 2015 - 07:51:35 EST


On Wed, Jan 14, 2015 at 11:46:58AM +0100, Philipp Zabel wrote:

> So the question is mostly whether four I2S data pins with a single
> shared WS/SCK input should be called "four I2S ports with shared clocks"
> or "one I2S port with up to four data lanes". I'd lean towards the
> latter.

Yes, this is what we're doing for the Samsung CPU side controllers which
implement this natively and seems to make sense here too - the different
channels can't really work as separate interfaces in any practical way.

> How audio2_i2s is forced to synchronize its clock output to audio1_i2s
> is a problem their bindings will have to handle.

Trying to hook up a controller that doesn't natively support this format
to a device that uses it is definitely tricky, as well as describing the
physical hookup we also need to worry about how things look to userspace
- it's ideally going to want a single multi-channel audio stream.

I think from a binding point of view we need a way to say "this endpoint
on the link is constructed from these DAIs on the device side" and say
if this is TDM or multi-data, and what's driving the clocks.

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