Date: Thu, 13 Apr 2017 15:45:44 -0500
From: Rob Herring <robh@kernel.org>
To: olivier moysan <olivier.moysan@st.com>
Cc: lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz,
        tiwai@suse.com, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com,
        alsa-devel@alsa-project.org, mark.rutland@arm.com,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        kernel@stlinux.com, linux-kernel@vger.kernel.org,
        arnaud.pouliquen@st.com, benjamin.gaignard@st.com
Subject: Re: [PATCH v4 1/2] ASoC: stm32: add bindings for SAI
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On Tue, Apr 11, 2017 at 05:47:25PM +0200, olivier moysan wrote:
> This patch adds documentation of device tree bindings for the
> STM32 SAI ASoC driver.
> 
> Signed-off-by: olivier moysan <olivier.moysan@st.com>
> ---
>  .../devicetree/bindings/sound/st,stm32-sai.txt     | 89 ++++++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> 
> diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> new file mode 100644
> index 0000000..c59a3d7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> @@ -0,0 +1,89 @@
> +STMicroelectronics STM32 Serial Audio Interface (SAI).
> +
> +The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
> +as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
> +The SAI contains two independent audio sub-blocks. Each sub-block has
> +its own clock generator and I/O lines controller.
> +
> +Required properties:
> +  - compatible: Should be "st,stm32f4-sai"
> +  - reg: Base address and size of SAI common register set.
> +  - clocks: Must contain phandle and clock specifier pairs for each entry
> +	in clock-names.
> +  - clock-names: Must contain "x8k" and "x11k"
> +	"x8k": SAI parent clock for sampling rates multiple of 8kHz.
> +	"x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
> +  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
> +
> +Optional properties:
> +  - resets: Reference to a reset controller asserting the SAI
> +
> +SAI subnodes:
> +Two subnodes corresponding to SAI sub-block instances A et B can be defined.
> +Subnode can be omitted for unsused sub-block.
> +
> +SAI subnodes required properties:
> +  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
> +	for SAI sub-block A or B respectively.
> +  - reg: Base address and size of SAI sub-block register set.
> +  - clocks: Must contain one phandle and clock specifier pair
> +	for sai_ck which feeds the internal clock generator.
> +  - clock-names: Must contain "sai_ck".
> +  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
> +  - dma-names: identifier string for each DMA request line
> +	"tx": if sai sub-block is configured as playback DAI
> +	"rx": if sai sub-block is configured as capture DAI
> +  - pinctrl-names: should contain only value "default"
> +  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
> +
> +Example:
> +sound_card {
> +	compatible = "audio-graph-card";
> +	dais = <&sai1b_port>;
> +};
> +
> +sai1: sai1@40015800 {
> +	compatible = "st,stm32f4-sai";
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	ranges;

It's preferred if this is not empty and it limited to the address range 
needed.

> +	reg = <0x40015800 0x4>;
> +	clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
> +	clock-names = "x8k", "x11k";
> +	interrupts = <87>;
> +
> +	sai1b: audio-controller@40015824 {
> +		#sound-dai-cells = <0>;
> +		compatible = "st,stm32-sai-sub-b";
> +		reg = <0x40015824 0x1C>;
> +		clocks = <&rcc 1 CLK_SAI2>;
> +		clock-names = "sai_ck";
> +		dmas = <&dma2 5 0 0x400 0x0>;
> +		dma-names = "tx";
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_sai1b>;
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			sai1b_port: port@0 {

Need to document how many ports and endpoints.

> +				reg = <0>;

For a single port, you don't need a reg prop.

> +				cpu_endpoint: endpoint {
> +					remote-endpoint = <&codec_endpoint>;
> +					audio-graph-card,format = "i2s";
> +					audio-graph-card,bitclock-master = <&codec_endpoint>;
> +					audio-graph-card,frame-master = <&codec_endpoint>;

The prefix is gone now.

> +				};
> +			};
> +		};
> +	};
> +};
> +
> +audio-codec {
> +	codec_port: port {
> +		codec_endpoint: endpoint {
> +			remote-endpoint = <&cpu_endpoint>;
> +		};
> +	};
> +};
> -- 
> 1.9.1
>