linux-kernel - Re: [PATCH v2 2/7] ASoC: audio-graph-card: Add plls and sysclks DT bindings

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Date:   Mon, 26 Oct 2020 08:27:04 -0500
From:   Rob Herring <robh@...nel.org>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>
Cc:     broonie@...nel.org, nsaenzjulienne@...e.de,
        patches@...nsource.cirrus.com, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rpi-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/7] ASoC: audio-graph-card: Add plls and sysclks DT
 bindings

On Fri, Oct 16, 2020 at 06:35:36PM +0100, Richard Fitzgerald wrote:
> This adds the two new properties 'plls' and 'sysclks' to the dt bindings.
> These add the ability to set values that will be
> passed to snd_soc_component_set_sysclk() and snd_soc_component_set_pll().

I worry this looks like Linux implementation details leaking into the 
binding.

> 
> Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
> ---
>  .../bindings/sound/audio-graph-card.txt       | 44 +++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/sound/audio-graph-card.txt b/Documentation/devicetree/bindings/sound/audio-graph-card.txt
> index d5f6919a2d69..59bbd5b55b59 100644
> --- a/Documentation/devicetree/bindings/sound/audio-graph-card.txt
> +++ b/Documentation/devicetree/bindings/sound/audio-graph-card.txt
> @@ -32,6 +32,19 @@ Required properties:
>  Optional properties:
>  - pa-gpios: GPIO used to control external amplifier.
>  
> +- plls: A list of component pll settings that will be applied with
> +      snd_soc_component_set_pll. Each entry is a phandle to the node of the
> +      codec or cpu component, followed by the four arguments id, source,
> +      frequency_in, frequency_out. Multiple entries can have the same phandle
> +      so that several plls can be set in the same component.

Where do the values of id and source come from?

> +
> +- sysclks: A list of component sysclk settings that will be applied with
> +      snd_soc_component_set_sysclk. Each entry is a phandle to the node of
> +      the codec or cpu component, followed by the four arguments id, source,
> +      frequency, direction. Direction is 0 if the clock is an input, 1 if it
> +      is an output. Multiple entries can have the same phandle so that several
> +      clocks can be set in the same component.

Are these really common properties? They seem kind of Cirrus specific 
and perhaps should be located in the codec node(s).

> +
>  -----------------------
>  Example: Single DAI case
>  -----------------------
> @@ -335,3 +348,34 @@ Example: Multi DAI with DPCM
>  			};
>  		};
>  	};
> +
> +-----------------------
> +Example: Set component sysclks and PLLs
> +-----------------------
> +
> +	sound {
> +		compatible = "audio-graph-card";
> +
> +		sysclks = <
> +			&cs47l15 1 4 98304000 0
> +			&cs47l15 8 4 147456000 0
> +		>;
> +		plls = <
> +			&cs47l15 1 0 24576000 98304000
> +		>;
> +
> +		dais = <&cpu_i2s_port>;
> +	};
> +
> +	cs47l15: codec@0 {
> +		...
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +			cs47l15_aif1_port: port@0 {
> +				reg = <0>;
> +				cs47l15_aif1: endpoint {
> +					remote-endpoint = <&cpu_i2s_endpoint>;
> +				};
> +			};
> +	};
> -- 
> 2.20.1
>