linux-kernel - Re: [PATCH v1 01/10] dt-bindings: media: Add Renesas CEU bindings

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Message-ID: <20171115123312.7fyhlpjsb3mp3ypc@valkosipuli.retiisi.org.uk>
Date:   Wed, 15 Nov 2017 14:33:12 +0200
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Jacopo Mondi <jacopo+renesas@...ndi.org>
Cc:     laurent.pinchart@...asonboard.com, magnus.damm@...il.com,
        geert@...der.be, mchehab@...nel.org, hverkuil@...all.nl,
        linux-renesas-soc@...r.kernel.org, linux-media@...r.kernel.org,
        linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 01/10] dt-bindings: media: Add Renesas CEU bindings

Hi Jacopo,

Thanks for the patchset. Please see my comments below.

On Wed, Nov 15, 2017 at 11:55:54AM +0100, Jacopo Mondi wrote:
> Add bindings documentation for Renesas Capture Engine Unit (CEU).
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
> ---
>  .../devicetree/bindings/media/renesas,ceu.txt      | 87 ++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/renesas,ceu.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/renesas,ceu.txt b/Documentation/devicetree/bindings/media/renesas,ceu.txt
> new file mode 100644
> index 0000000..a88e9cb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/renesas,ceu.txt
> @@ -0,0 +1,87 @@
> +Renesas Capture Engine Unit (CEU)
> +----------------------------------------------
> +
> +The Capture Engine Unit is the image capture interface found on Renesas
> +RZ chip series and on SH Mobile ones.
> +
> +The interface supports a single parallel input with up 8/16bits data bus width.
> +
> +Required properties:
> +- compatible
> +	Must be "renesas,renesas-ceu".
> +- reg
> +	Physical address base and size.
> +- interrupts
> +	The interrupt line number.
> +- pinctrl-names, pinctrl-0
> +	phandle of pin controller sub-node configuring pins for CEU operations.
> +
> +CEU supports a single parallel input and should contain a single 'port' subnode
> +with a single 'endpoint'. Optional endpoint properties applicable to parallel
> +input bus are described in "video-interfaces.txt".

Could you list which ones they are? For someone not familiar with the
parallel bus this might not be obvious; also not all hardware can make use
of every one of these properties.

> +
> +Example:
> +
> +The example describes the connection between the Capture Engine Unit and a
> +OV7670 image sensor sitting on bus i2c1 with an on-board 24Mhz clock.
> +
> +ceu: ceu@...10000 {
> +	reg = <0xe8210000 0x209c>;
> +	compatible = "renesas,renesas-ceu";
> +	interrupts = <GIC_SPI 332 IRQ_TYPE_LEVEL_HIGH>;
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&vio_pins>;
> +
> +	status = "okay";
> +
> +	port {
> +		ceu_in: endpoint {
> +			remote-endpoint = <&ov7670_out>;
> +
> +			bus-width = <8>;
> +			hsync-active = <1>;
> +			vsync-active = <1>;
> +			pclk-sample = <1>;
> +			data-active = <1>;
> +		};
> +	};
> +};
> +
> +i2c1: i2c@...ee400 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&i2c1_pins>;
> +
> +	status = "okay";
> +	clock-frequency = <100000>;
> +
> +	ov7670: camera@21 {
> +		compatible = "ovti,ov7670";
> +		reg = <0x21>;
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&vio_pins>;
> +
> +		reset-gpios = <&port3 11 GPIO_ACTIVE_LOW>;
> +		powerdown-gpios = <&port3 12 GPIO_ACTIVE_HIGH>;
> +
> +		clocks = <&xclk>;
> +		clock-names = "xclk";
> +
> +		xclk: fixed_clk {
> +			compatible = "fixed-clock";
> +			#clock-cells = <0>;
> +			clock-frequency = <24000000>;
> +		};

What's the purpose of the fixed_clk node here?

> +
> +		port {
> +			ov7670_out: endpoint {
> +				remote-endpoint = <&ceu_in>;
> +
> +				bus-width = <8>;
> +				hsync-active = <1>;
> +				vsync-active = <1>;
> +				pclk-sample = <1>;
> +				data-active = <1>;
> +			};
> +		};
> +	};

-- 
Regards,

Sakari Ailus
e-mail: sakari.ailus@....fi