Re: [PATCH 1/2] dt-bindings: sound: lpass-cpu: Document DAI subnodes

[Rob Herring <robh@kernel.org>]

On Mon, Apr 06, 2020 at 03:56:07PM +0200, Stephan Gerhold wrote:
> The lpass-cpu driver now allows configuring the MI2S SD lines
> by defining subnodes for one of the DAIs.
> 
> Document this in the device tree bindings.
> 
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> ---
>  .../bindings/sound/qcom,lpass-cpu.txt         | 23 +++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/sound/qcom,lpass-cpu.txt b/Documentation/devicetree/bindings/sound/qcom,lpass-cpu.txt
> index 21c648328be9..df53a10502f7 100644
> --- a/Documentation/devicetree/bindings/sound/qcom,lpass-cpu.txt
> +++ b/Documentation/devicetree/bindings/sound/qcom,lpass-cpu.txt
> @@ -30,6 +30,8 @@ Required properties:
>  - reg			: Must contain an address for each entry in reg-names.
>  - reg-names		: A list which must include the following entries:
>  				* "lpass-lpaif"
> +- #address-cells	: Must be 1
> +- #size-cells		: Must be 0
>  
>  
>  
> @@ -37,6 +39,18 @@ Optional properties:
>  
>  - qcom,adsp		: Phandle for the audio DSP node
>  
> +By default, the driver uses up to 4 MI2S SD lines, for a total of 8 channels.
> +The SD lines to use can be configured by adding subnodes for each of the DAIs.
> +
> +Required properties for each DAI (represented by a subnode):
> +- reg			: Must be one of the DAI IDs
> +			  (usually part of dt-bindings header)
> +- qcom,playback-sd-lines: List of serial data lines (0-3) to use for playback

0-3 for the values or number of entries?

> +- qcom,capture-sd-lines	: List of serial data lines (0-3) to use for capture
> +
> +Note that adding a subnode changes the default to "no lines configured",
> +so both playback and capture lines should be configured when a subnode is added.
> +
>  Example:
>  
>  lpass@28100000 {
> @@ -51,4 +65,13 @@ lpass@28100000 {
>  	reg = <0x28100000 0x10000>;
>  	reg-names = "lpass-lpaif";
>  	qcom,adsp = <&adsp>;
> +
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	/* Optional to set different MI2S SD lines */
> +	mi2s-quaternary@3 {

Normally the node name reflects the class of device. IOW, all the child 
nodes should have the same name.

> +		reg = <MI2S_QUATERNARY>;
> +		qcom,playback-sd-lines = <0 1>;
> +	};
>  };
> -- 
> 2.26.0
>