Subject: Re: [PATCH v10 2/2] ASoC: fsl: Add S/PDIF machine driver

From: Stephen Warren <[email-masked]>
Date: Wed, 21 Aug 2013 12:30:59 -0600

On 08/20/2013 09:13 PM, Nicolin Chen wrote:
> This patch implements a device-tree-only machine driver for Freescale
> i.MX series Soc. It works with spdif_transmitter/spdif_receiver and
> fsl_spdif.c drivers.

> diff --git a/Documentation/devicetree/bindings/sound/imx-audio-spdif.txt b/Documentation/devicetree/bindings/sound/imx-audio-spdif.txt

> +Optional properties:
> +
> +  - spdif-transmitter : The phandle of the spdif-transmitter codec
> +
> +  - spdif-receiver : The phandle of the spdif-receiver codec
> +
> +* Note: At least one of these two properties should be set in the DT binding.

I still don't think those two properties are correct.

Exactly what node will those phandles point at?

There definitely should not be a DT node for any "dummy CODEC",
irrespective of whether this binding calls the other node a "CODEC" or a
"dummy CODEC".

If these properties are to contain phandles, it would be acceptable for
the referenced node to be:

* A node representing the physical connector/jack on the board.

* A node representing some other IP block on the board, such as an HDMI
encoder/display-controller

I think those options are unlikely in general, so I think instead these
properties should just be Boolean indicating that "something" is
connector to the S/PDIF RX/TX, without specifying what that "something"
is. It doesn't matter what at least in the connector/jack case, although
perhaps it does in the HDMI encoder/display-controller?