linux-kernel - Re: [PATCH 2/2] [media] atmel-isc: DT binding for Image Sensor Controller driver

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Message-ID: <20160414152933.GA14073@rob-hp-laptop>
Date:	Thu, 14 Apr 2016 10:29:33 -0500
From:	Rob Herring <robh@...nel.org>
To:	Songjun Wu <songjun.wu@...el.com>
Cc:	g.liakhovetski@....de, nicolas.ferre@...el.com,
	linux-arm-kernel@...ts.infradead.org,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] [media] atmel-isc: DT binding for Image Sensor
 Controller driver

On Wed, Apr 13, 2016 at 03:44:20PM +0800, Songjun Wu wrote:
> DT binding documentation for ISC driver.
> 
> Signed-off-by: Songjun Wu <songjun.wu@...el.com>
> ---
> 
>  .../devicetree/bindings/media/atmel-isc.txt        | 84 ++++++++++++++++++++++
>  1 file changed, 84 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/atmel-isc.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/atmel-isc.txt b/Documentation/devicetree/bindings/media/atmel-isc.txt
> new file mode 100644
> index 0000000..449f05f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/atmel-isc.txt
> @@ -0,0 +1,84 @@
> +Atmel Image Sensor Controller (ISC)
> +----------------------------------------------
> +
> +Required properties:
> +- compatible
> +	Must be "atmel,sama5d2-isc"
> +- reg
> +	Physical base address and length of the registers set for the device;
> +- interrupts
> +  Should contain IRQ line for the ISI;
> +- clocks
> +	List of clock specifiers, corresponding to entries in
> +	the clock-names property;
> +	Please refer to clock-bindings.txt.
> +- clock-names
> +	Required elements: "hclock", "ispck".
> +- pinctrl-names, pinctrl-0
> +	Please refer to pinctrl-bindings.txt.
> +- clk_in_isc

No underscores and this needs a better explanation.

> +	ISC internal clock node, it includes the isc_ispck and isc_mck.
> +	Please refer to clock-bindings.txt.
> +- atmel,sensor-preferred
> +	Sensor is preferred to process image (1-preferred, 0-not).
> +	The default value is 1.

This seems a bit questionable.

> +
> +ISC supports a single port node with parallel bus. It should contain one
> +'port' child node with child 'endpoint' node. Please refer to the bindings
> +defined in Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +Example:
> +isc: isc@...08000 {
> +	compatible = "atmel,sama5d2-isc";
> +	reg = <0xf0008000 0x4000>;
> +	interrupts = <46 IRQ_TYPE_LEVEL_HIGH 5>;
> +	clocks = <&isc_clk>, <&isc_ispck>;
> +	clock-names = "hclock", "ispck";
> +	atmel,sensor-preferred = <1>;
> +
> +	port {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		isc_0: endpoint@0 {

Don't need a unit address for a single endpoint.

> +			remote-endpoint = <&ov7740_0>;
> +			hsync-active = <1>;
> +			vsync-active = <0>;
> +			pclk-sample = <1>;

Are these documented? They are really properties of the sensor and 
should be part of the sensor node.

> +		};
> +	};
> +
> +	clk_in_isc {

Completely missed this is a node from the above description. I should be 
able to write or validate the example from the description.

I think perhaps you should just drop all this from the DT, just list the 
input clocks, and make the ISC node the clock controller.

> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		isc_ispck: isc_ispck {

No underscores in node names.

> +			#clock-cells = <0>;
> +			reg = <0>;

Drop or you need a unit address.

> +			clocks = <&isc_clk>, <&iscck>;
> +		};
> +
> +		isc_mck: isc_mck {
> +			#clock-cells = <0>;
> +			reg = <1>;
> +			clocks = <&isc_clk>, <&iscck>, <&isc_gclk>;
> +		};
> +	};
> +};
> +
> +i2c1: i2c@...28000 {
> +	ov7740: camera@...1 {

Drop "0x"

> +	compatible = "ovti,ov7740";
> +	reg = <0x21>;
> +
> +	clocks = <&isc_mck>;
> +	clock-names = "xvclk";
> +	assigned-clocks = <&isc_mck>;
> +	assigned-clock-rates = <24000000>;
> +
> +	port {
> +		ov7740_0: endpoint {
> +			remote-endpoint = <&isc_0>;
> +		};
> +	};
> +};
> -- 
> 2.7.4
> 
> --
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