linux-kernel - Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes.

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Message-ID: <1579603.xgvSgGFBs8@avalon>
Date:   Tue, 16 May 2017 00:53:22 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Eric Anholt <eric@...olt.net>,
        Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes.

Hi Eric,

Thank you for the patch.

On Thursday 11 May 2017 16:56:23 Eric Anholt wrote:
> The Raspberry Pi 7" Touchscreen is a DPI touchscreen panel with
> DSI->DPI bridge and touchscreen controller integrated, that connects
> to the Raspberry Pi through its 15-pin "DSI" connector (some lines are
> DSI, some lines are I2C).
> 
> This device is represented in the DT as three nodes (DSI device, I2C
> device, panel).  Input will be left to a separate binding later, as it
> will be a basic I2C client device.
> 
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>  .../raspberrypi,7inch-touchscreen-bridge.txt       | 68 +++++++++++++++++++
>  .../panel/raspberrypi,7inch-touchscreen-panel.txt  |  7 +++
>  2 files changed, 75 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touchscr
> een-bridge.txt create mode 100644
> Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscre
> en-panel.txt
> 
> diff --git
> a/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touchs
> creen-bridge.txt
> b/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touchs
> creen-bridge.txt new file mode 100644
> index 000000000000..a5669beaf68f
> --- /dev/null
> +++
> b/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touchs
> creen-bridge.txt @@ -0,0 +1,68 @@
> +Official 7" (800x480) Raspberry Pi touchscreen panel's bridge.
> +
> +This DSI panel contains:
> +
> +- TC358762 DSI->DPI bridge
> +- Atmel microcontroller on I2C for power sequencing the DSI bridge and
> +  controlling backlight
> +- Touchscreen controller on I2C for touch input
> +
> +and this covers the TC358762 bridge and Atmel microcontroller, while
> +../panel/raspberrypi,7inch-touchscreen-panel.txt covers the panel.

The TC358762 is a standalone bridge that doesn't depend on the ATTiny 
microcontroller used by the RPI. As it's usable standalone, I believe this 
binding should be split in two.

> +Required properties:
> +- compatible:	Must be "raspberrypi,7inch-touchscreen-bridge"
> +- raspberrypi,touchscreen-bridge:
> +		Handle to the I2C device for Atmel microcontroller
> +
> +Example:
> +
> +dsi1: dsi@...00000 {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	<...>
> +
> +	lcd-bridge@0 {
> +		compatible = "raspberrypi,7inch-touchscreen-bridge";
> +		reg = <0>;
> +
> +		raspberrypi,touchscreen-bridge = <&pitouchscreen_bridge>;
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +			port@0 {
> +				reg = <0>;
> +				pitouchscreen_bridge_port: endpoint {
> +					remote-endpoint = 
<&pitouchscreen_panel_port>;
> +				};
> +			};
> +		};
> +	};
> +};
> +
> +i2c_dsi: i2c {
> +	compatible = "i2c-gpio";
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	gpios = <&gpio 28 0
> +		 &gpio 29 0>;
> +
> +	pitouchscreen_bridge: bridge@45 {
> +		compatible = "raspberrypi,touchscreen-bridge-i2c";
> +		reg = <0x45>;
> +	};
> +};
> +
> +lcd {
> +	compatible = "raspberrypi,7inch-touchscreen-panel";
> +	ports {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		port@0 {
> +			reg = <0>;
> +			pitouchscreen_panel_port: endpoint {
> +				remote-endpoint = 
<&pitouchscreen_bridge_port>;
> +			};
> +		};
> +	};
> +};
> diff --git
> a/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchsc
> reen-panel.txt
> b/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchsc
> reen-panel.txt new file mode 100644
> index 000000000000..1e84f97b3b20
> --- /dev/null
> +++
> b/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchsc
> reen-panel.txt @@ -0,0 +1,7 @@
> +Official 7" (800x480) Raspberry Pi touchscreen panel's panel.
> +
> +This binding is compatible with the simple-panel binding, which is
> specified +in simple-panel.txt in this directory.
> +
> +Required properties:
> +- compatible:	Must be "raspberrypi,7inch-touchscreen-panel"

-- 
Regards,

Laurent Pinchart