[alsa-devel] [PATCH] ASoC: generic: Add generic DT based simple codec

Stephen Warren swarren at wwwdotorg.org
Mon Sep 30 18:49:06 CEST 2013

On 09/26/2013 08:57 PM, Rob Herring wrote:
> On Mon, Sep 23, 2013 at 4:19 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
>> On 09/19/2013 02:54 AM, Jean-Francois Moine wrote:
>>> This patch adds a simple sound codec which is described by the DT.
>>> This codec may be used when no specific codec action is needed.
>>> diff --git a/Documentation/devicetree/bindings/sound/simple-codec.txt b/Documentation/devicetree/bindings/sound/simple-codec.txt
>>> +Device-Tree bindings for the simple codec
>>> +
>>> +Required properties:
>>> +- compatible: should be "linux,simple-codec".
>> We shouldn't have any Linux-specific bindings. It might be reasonable to
>> define a binding for a "simple CODEC", but there's no reason it should
>> be Linux-specific.
> Further, just define the type of codec h/w. If linux can use its
> simple-codec driver for it, then add a match table entry for said
> codec. Then the DT is future proof when you decide the simple driver
> doesn't really work for that h/w.

The only potential issue with that approach is if the CODEC can be used
in a "simple" mode where e.g. no control GPIOs, regulator manipulation,
etc. are required, or in a more complex mode where such things are
required, you may end up with the device-specific binding being written
to the simple mode, and hence missing features required for the complex
mode. Having a separate simple binding prevents the device-specific
binding from being broken that way.

That said, it's probably better to simply get the device-specific
binding completely fleshed out and representing all resources the first
time around, then there's no issue either.

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