linux-kernel - Re: [PATCH 3/3] arm64: dts: renesas: draak: Describe HDMI input

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Date:   Sun, 13 May 2018 14:57:55 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Jacopo Mondi <jacopo+renesas@...ndi.org>
Cc:     laurent.pinchart@...asonboard.com, horms@...ge.net.au,
        geert@...der.be, magnus.damm@...il.com, robh+dt@...nel.org,
        linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] arm64: dts: renesas: draak: Describe HDMI input

Hi Jacopo,

Thanks for your patch.

On 2018-05-11 12:00:02 +0200, Jacopo Mondi wrote:
> Describe HDMI input connected to VIN4 interface for R-Car D3 Draak
> development board.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
> ---
>  arch/arm64/boot/dts/renesas/r8a77995-draak.dts | 68 ++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/renesas/r8a77995-draak.dts b/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
> index d03f194..e0ce462 100644
> --- a/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
> +++ b/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
> @@ -59,6 +59,17 @@
>  		};
>  	};
>  
> +	hdmi-in {
> +		compatible = "hdmi-connector";
> +		type = "a";
> +
> +		port {
> +			hdmi_con_in: endpoint {
> +				remote-endpoint = <&adv7612_in>;
> +			};
> +		};
> +	};
> +
>  	memory@...00000 {
>  		device_type = "memory";
>  		/* first 128MB is reserved for secure area. */
> @@ -142,6 +153,11 @@
>  		groups = "usb0";
>  		function = "usb0";
>  	};
> +
> +	vin4_pins: vin4 {
> +		groups = "vin4_data24", "vin4_sync", "vin4_clk", "vin4_clkenb";
> +		function = "vin4";
> +	};
>  };
>  
>  &i2c0 {
> @@ -154,6 +170,35 @@
>  		reg = <0x50>;
>  		pagesize = <8>;
>  	};
> +
> +	hdmi-decoder@4c {
> +		compatible = "adi,adv7612";
> +		reg = <0x4c>;
> +		default-input = <0>;
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;
> +				adv7612_in: endpoint {
> +					remote-endpoint = <&hdmi_con_in>;
> +				};
> +			};
> +
> +			port@2 {
> +				reg = <2>;
> +				adv7612_out: endpoint {
> +					pclk-sample = <0>;
> +					hsync-active = <0>;
> +					vsync-active = <0>;

This differs from the Gen2 DT bindings which is a very similar hardware 
setup using the same components. Defining these properties will make the 
bus marked as V4L2_MBUS_PARALLEL instead of V4L2_MBUS_BT656.

This will change how the hardware is configured for capture if the media 
bus is in a UYVY format, see VNMC_INF register in rvin_setup(). Maybe 
this it not an issue here but still I'm curious to why this differ 
between Gen2 and Gen3 :-)

> +
> +					remote-endpoint = <&vin4_in>;
> +				};
> +			};
> +		};
> +	};
>  };
>  
>  &i2c1 {
> @@ -246,3 +291,26 @@
>  	timeout-sec = <60>;
>  	status = "okay";
>  };
> +
> +&vin4 {
> +	pinctrl-0 = <&vin4_pins>;
> +	pinctrl-names = "default";
> +
> +	status = "okay";
> +
> +	ports {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		port@0 {
> +			reg = <0>;
> +
> +			vin4_in: endpoint {
> +				hsync-active = <0>;
> +				vsync-active = <0>;

Comparing this to the Gen2 bindings some properties are missing,

bus-width = <24>;
pclk-sample = <1>;
data-active = <1>;

This is not a big deal as the VIN driver don't use these properties so 
no functional change should come of this but still a difference.  

Over all I'm happy with this change but before I add my tag I would like 
to understand why it differs from the Gen2 configuration for the adv7612 
properties.

Also on a side not it is possible with hardware switches on the board 
switch the VIN4 source to a completely different pipeline CVBS connector 
-> adv7180 -> VIN4. But I think it's best we keep the HDMI as default as 
this seems to be how the boards are shipped. But maybe mentioning this 
in the commit message would not hurt if you end-up resending the patch.

> +
> +				remote-endpoint = <&adv7612_out>;
> +			};
> +		};
> +	};
> +};
> -- 
> 2.7.4
> 

-- 
Regards,
Niklas Söderlund