Display panels hardware components

Applicable for

STM32MP13x lines, STM32MP15x lines

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1. Article purpose

The purpose of this article is to:

• List the display panel hardware components that might be integrated in the different boards.
• Link these components to the corresponding software framework(s).
• Point to the appropriate component datasheets.
• Explain, when necessary, how to configure these components.

2. Software frameworks

Domain	Peripheral	Software components			Comment
		OP-TEE	Linux	STM32Cube
Visual	Raydium RM68200		DRM/KMS framework		MIPI® DSI panel driver
Visual	Orise Tech OTM8009a		DRM/KMS framework		MIPI® DSI panel driver
Visual	Raspberry Pi 7" Touch		DRM/KMS framework		MIPI® DSI panel driver
Visual	Rocktech rk043fn48h		DRM/KMS framework		Parallel RGB (DPI) panel driver

3. Raydium RM68200

The Raydium RM68200 is a single-chip solution for a-Si TFT LCD that incorporates gate drivers and is capable of driving different panel resolutions. It supports MIPI^® DSI Interface.

For details and the datasheet please contact the RM68200 driver provider.

Information

This panel driver can be found on some STM32MP15 Evaluation boards.

3.1. Linux driver

Bindings: Documentation/devicetree/bindings/display/panel/raydium,rm68200.yaml

Sources: drivers/gpu/drm/panel/panel-raydium-rm68200.c

Configuration: DRM_PANEL_RAYDIUM_RM68200

Click here to show the example

Devicetree example: arch/arm/boot/dts/stm32mp157d-ev1.dts

/ {
...
	panel_backlight: panel-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpiod 13 GPIO_ACTIVE_LOW>;
		default-on;
		status = "okay";
	};
};

&dsi {
	#address-cells = <1>;
	#size-cells = <0>;
	status = "okay";

	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		port@0 {
			reg = <0>;
			dsi_in: endpoint {
				remote-endpoint = <&ltdc_ep0_out>;
			};
		};

		port@1 {
			reg = <1>;
			dsi_out: endpoint {
				remote-endpoint = <&dsi_panel_in>;
			};
		};
	};

	panel_dsi: panel-dsi@0 {
		compatible = "raydium,rm68200";
		reg = <0>;
		reset-gpios = <&gpiof 15 GPIO_ACTIVE_LOW>;
		backlight = <&panel_backlight>;
		power-supply = <&v3v3>;
		status = "okay";

		port {
			dsi_panel_in: endpoint {
				remote-endpoint = <&dsi_out>;
			};
		};
	};
};

&i2c2 {
	gt9147: goodix_ts@5d {
		compatible = "goodix,gt9147";
		reg = <0x5d>;
		panel = <&panel_dsi>;
		pinctrl-0 = <&goodix_pins>;
		pinctrl-names = "default";
		status = "okay";

		interrupts = <14 IRQ_TYPE_EDGE_RISING>;
		interrupt-parent = <&stmfx_pinctrl>;
	};
};

&ltdc {
	status = "okay";

	port {
		ltdc_ep0_out: endpoint@0 {
			reg = <0>;
			remote-endpoint = <&dsi_in>;
		};
	};
};

3.2. U-Boot driver

Bindings: drivers/video/raydium-rm68200.c

4. Orise Tech OTM8009a

The Orise Tech OTM8009a is a MIPI^® DSI panel driver.

For details and the datasheet please contact the OTM8009a driver provider.

Information

This panel driver can be found on some STM32MP15 Discovery kits.

4.1. Linux driver

Bindings: Documentation/devicetree/bindings/display/panel/orisetech,otm8009a.yaml

Sources: drivers/gpu/drm/panel/panel-orisetech-otm8009a.c

Configuration: DRM_PANEL_RAYDIUM_RM68200

Click here to show the example

Devicetree example: arch/arm/boot/dts/stm32mp157f-dk2.dts

&dsi {
	status = "okay";

	ports {
		port@0 {
			reg = <0>;
			dsi_in: endpoint {
				remote-endpoint = <&ltdc_ep1_out>;
			};
		};

		port@1 {
			reg = <1>;
			dsi_out: endpoint {
				remote-endpoint = <&panel_in>;
			};
		};
	};

	panel_otm8009a: panel-otm8009a@0 {
		compatible = "orisetech,otm8009a";
		reg = <0>;
		reset-gpios = <&gpioe 4 GPIO_ACTIVE_LOW>;
		power-supply = <&v3v3>;
		status = "okay";

		port {
			panel_in: endpoint {
				remote-endpoint = <&dsi_out>;
			};
		};
	};
};

&i2c1 {
	touchscreen@2a {
		compatible = "focaltech,ft6236";
		reg = <0x2a>;
		interrupts = <2 2>;
		interrupt-parent = <&gpiof>;
		interrupt-controller;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <800>;
		panel = <&panel_otm8009a>;
		vcc-supply = <&v3v3>;
		iovcc-supply = <&v3v3>;
		status = "okay";
	};
	touchscreen@38 {
		compatible = "focaltech,ft6236";
		reg = <0x38>;
		interrupts = <2 2>;
		interrupt-parent = <&gpiof>;
		interrupt-controller;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <800>;
		panel = <&panel_otm8009a>;
		vcc-supply = <&v3v3>;
		iovcc-supply = <&v3v3>;
		status = "okay";
	};
};

&ltdc {
	status = "okay";

	port {
		ltdc_ep1_out: endpoint@1 {
			reg = <1>;
			remote-endpoint = <&dsi_in>;
		};
	};
};

4.2. U-Boot driver

Bindings: drivers/video/orisetech_otm8009a.c

5. Raspberry Pi 7" Touch

The Raspberry Pi 7" Touch Display is an integrated module including:

• a DSI to DPI bridge Toshiba TC358762;
• a DPI panel 800x480 7 inches with touchscreen;
• a power controller;
• a touchscreen controller.

For details and datasheet please contact the display provider .

The display can be plugged in the DSI connector CN4 of the board STM32MP157F-DK2 through the ribbon cable provided with the display.

Warning

An incorrect connection could damage either the display and/or the board.

Pay attention that the connector CN4 is wider than the ribbon cable; the proper connection requires the pin 1 of the ribbon cable to be plugged at the pin 1 of CN4. This requires the ribbon cable to touch only the edge of the connector CN4 that is closer to the ethernet plug, thus having empty space between the ribbon cable and the other edge of the connector CN4.

Two additional wires for 5V supply and GND are required between STM32MP157F-DK2 board and the display. Don't use a USB cable to power the display from the board because the board's USB plugs would be enabled too late for the display to operate. Use instead two of the spare wires provided with the display and connect:

• STM32MP157F-DK2 connector CN2 pin 2 to display connector GPIO pin 5V;
• STM32MP157F-DK2 connector CN2 pin 6 to display connector GPIO pin GND.

5.1. Linux driver

Bindings:

• Documentation/devicetree/bindings/display/bridge/toshiba,tc358762.yaml
• Documentation/devicetree/bindings/display/panel/panel-simple.yaml
• Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator.yaml

Sources:

• drivers/gpu/drm/bridge/tc358762.c
• drivers/gpu/drm/panel/panel-simple.c
• drivers/regulator/rpi-panel-attiny-regulator.c

Configuration:

• DRM_TOSHIBA_TC358762
• DRM_PANEL_SIMPLE
• REGULATOR_RASPBERRYPI_TOUCHSCREEN_ATTINY

Information

Different versions of the panel use different touchscreen controllers. The touchscreen is not further described here.

Information

Don't use the old driver Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.yaml . It has been replaced by the new driver since kernel v5.10.

Click here to show the example

Devicetree example:

&dsi {
	status = "okay";

	ports {
		port@0 {
			reg = <0>;
			dsi_in: endpoint {
				remote-endpoint = <&ltdc_ep1_out>;
			};
		};

		port@1 {
			reg = <1>;
			dsi_out: endpoint {
				remote-endpoint = <&bridge_in>;
			};
		};
	};

	bridge@0 {
		compatible = "toshiba,tc358762";
		reg = <0>;
		vddc-supply = <&reg_rpi>;
		status = "okay";

		ports {
			#address-cells = <1>;
			#size-cells = <0>;

			port@0 {
				reg = <0>;
				bridge_in: endpoint {
					remote-endpoint = <&dsi_out>;
				};
			};
			port@1 {
				reg = <1>;
				bridge_out: endpoint {
					remote-endpoint = <&panel_in>;
				};
			};
		};
	};
};

/ {
	panel-rgb {
		/* Unknown; use a reasonably similar one */
		compatible = "powertip,ph800480t013-idf02";
		power-supply = <&reg_rpi>;
		status = "okay";

		port {
			panel_in: endpoint {
				remote-endpoint = <&bridge_out>;
			};
		};
	};
};

&i2c1 {
	reg_rpi: regulator@45 {
		compatible = "raspberrypi,7inch-touchscreen-panel-regulator";
		reg = <0x45>;
		vin-supply = <&v3v3>;
		status = "okay";
	};
};

5.2. U-Boot driver

Not available.

6. Rocktech rk043fn48h

The Rocktech rk043fn48h is a parallel RGB panel driver.

For details and the datasheet please contact the rk043fn48h driver provider.

Information

This panel driver can be found on some STM32MP13 Discovery kits.

6.1. Linux driver

Bindings: Documentation/devicetree/bindings/display/panel/panel-dpi.yaml

Sources: drivers/gpu/drm/panel/panel-simple.c

Configuration: DRM_PANEL_SIMPLE

Click here to show the example

Devicetree example: arch/arm/boot/dts/stm32mp135f-dk.dts

/ {
...
	panel_backlight: panel-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpioe 12 GPIO_ACTIVE_HIGH>;
		default-on;
		default-brightness-level = <0>;
		status = "okay";
	};

	panel_rgb: panel-rgb {
		compatible = "rocktech,rk043fn48h", "panel-dpi";
		enable-gpios = <&gpioi 7 GPIO_ACTIVE_HIGH>;
		backlight = <&panel_backlight>;
		power-supply = <&scmi_v3v3_sw>;
		status = "okay";

		width-mm = <105>;
		height-mm = <67>;

		port {
			panel_in_rgb: endpoint {
				remote-endpoint = <&ltdc_out_rgb>;
			};
		};

		panel-timing {
			clock-frequency = <10000000>;
			hactive = <480>;
			vactive = <272>;
			hsync-len = <52>;
			hfront-porch = <10>;
			hback-porch = <10>;
			vsync-len = <10>;
			vfront-porch = <10>;
			vback-porch = <10>;
		};
	};

...
};

&i2c5 {
...
	goodix: goodix_ts@5d {
		compatible = "goodix,gt911";
		reg = <0x5d>;
		pinctrl-names = "default";
		pinctrl-0 = <&goodix_pins_a>;
		interrupt-parent = <&gpiof>;
		interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
	        reset-gpios = <&gpioh 2 GPIO_ACTIVE_LOW>;
	        AVDD28-supply = <&scmi_v3v3_sw>;
	        VDDIO-supply = <&scmi_v3v3_sw>;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <272>;
		status = "okay" ;
	};
};

&ltdc {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&ltdc_pins_a>;
	pinctrl-1 = <&ltdc_sleep_pins_a>;
	status = "okay";

	port {
		#address-cells = <1>;
		#size-cells = <0>;

		ltdc_out_rgb: endpoint@0 {
			reg = <0>;
			remote-endpoint = <&panel_in_rgb>;
		};
	};
};

Click here to show the example

Devicetree pin control bindings example: arch/arm/boot/dts/stm32mp13-pinctrl.dtsi

&pinctrl {
...
	ltdc_pins_a: ltdc-0 {
		pins {
			pinmux = <STM32_PINMUX('D',  9, AF13)>, /* LCD_CLK */
				 <STM32_PINMUX('C',  6, AF14)>, /* LCD_HSYNC */
				 <STM32_PINMUX('G',  4, AF11)>, /* LCD_VSYNC */
				 <STM32_PINMUX('H',  9, AF11)>, /* LCD_DE */
				 <STM32_PINMUX('G',  7, AF14)>, /* LCD_R2 */
				 <STM32_PINMUX('B', 12, AF13)>, /* LCD_R3 */
				 <STM32_PINMUX('D', 14, AF14)>, /* LCD_R4 */
				 <STM32_PINMUX('E',  7, AF14)>, /* LCD_R5 */
				 <STM32_PINMUX('E', 13, AF14)>, /* LCD_R6 */
				 <STM32_PINMUX('E',  9, AF14)>, /* LCD_R7 */
				 <STM32_PINMUX('H', 13, AF14)>, /* LCD_G2 */
				 <STM32_PINMUX('F',  3, AF14)>, /* LCD_G3 */
				 <STM32_PINMUX('D',  5, AF14)>, /* LCD_G4 */
				 <STM32_PINMUX('G',  0, AF14)>, /* LCD_G5 */
				 <STM32_PINMUX('C',  7, AF14)>, /* LCD_G6 */
				 <STM32_PINMUX('A', 15, AF11)>, /* LCD_G7 */
				 <STM32_PINMUX('D', 10, AF14)>, /* LCD_B2 */
				 <STM32_PINMUX('F',  2, AF14)>, /* LCD_B3 */
				 <STM32_PINMUX('H', 14, AF11)>, /* LCD_B4 */
				 <STM32_PINMUX('E',  0, AF14)>, /* LCD_B5 */
				 <STM32_PINMUX('B',  6, AF7)>,  /* LCD_B6 */
				 <STM32_PINMUX('F',  1, AF13)>; /* LCD_B7 */
			bias-disable;
			drive-push-pull;
			slew-rate = <0>;
		};
	};

	ltdc_sleep_pins_a: ltdc-sleep-0 {
		pins {
			pinmux = <STM32_PINMUX('D',  9, ANALOG)>, /* LCD_CLK */
				 <STM32_PINMUX('C',  6, ANALOG)>, /* LCD_HSYNC */
				 <STM32_PINMUX('G',  4, ANALOG)>, /* LCD_VSYNC */
				 <STM32_PINMUX('H',  9, ANALOG)>, /* LCD_DE */
				 <STM32_PINMUX('G',  7, ANALOG)>, /* LCD_R2 */
				 <STM32_PINMUX('B', 12, ANALOG)>, /* LCD_R3 */
				 <STM32_PINMUX('D', 14, ANALOG)>, /* LCD_R4 */
				 <STM32_PINMUX('E',  7, ANALOG)>, /* LCD_R5 */
				 <STM32_PINMUX('E', 13, ANALOG)>, /* LCD_R6 */
				 <STM32_PINMUX('E',  9, ANALOG)>, /* LCD_R7 */
				 <STM32_PINMUX('H', 13, ANALOG)>, /* LCD_G2 */
				 <STM32_PINMUX('F',  3, ANALOG)>, /* LCD_G3 */
				 <STM32_PINMUX('D',  5, ANALOG)>, /* LCD_G4 */
				 <STM32_PINMUX('G',  0, ANALOG)>, /* LCD_G5 */
				 <STM32_PINMUX('C',  7, ANALOG)>, /* LCD_G6 */
				 <STM32_PINMUX('A', 15, ANALOG)>, /* LCD_G7 */
				 <STM32_PINMUX('D', 10, ANALOG)>, /* LCD_B2 */
				 <STM32_PINMUX('F',  2, ANALOG)>, /* LCD_B3 */
				 <STM32_PINMUX('H', 14, ANALOG)>, /* LCD_B4 */
				 <STM32_PINMUX('E',  0, ANALOG)>, /* LCD_B5 */
				 <STM32_PINMUX('B',  6, ANALOG)>, /* LCD_B6 */
				 <STM32_PINMUX('F',  1, ANALOG)>; /* LCD_B7 */
		};
	};

};

6.2. U-Boot driver

Bindings: drivers/video/simple_panel.c

Open portable trusted execution environment

Linux^® is a registered trademark of Linus Torvalds.

Mobile Industry Processor Interface, open membership organization that includes leading companies in the mobile industry that share the objective of defining and promoting open specifications for interfaces inside mobile terminals, see MIPI^® Alliance standard web site https://www.mipi.org

Display serial interface (MIPI^® Alliance standard)

Display pixel interface (MIPI^® Alliance standard)

Direct rendering manager (kernel module that gives direct hardware access to DRI clients, find more information on official DRI web site http://dri.freedesktop.org/wiki/DRM)

General-purpose input/output (A realization of open ended transmission between devices on an embedded level. These pins available on a processor can be programmed to be used to either accept input or provide output to external devices depending on user desires and applications requirements.)

Das U-Boot -- the universal boot loader (see U-Boot)

Linux^® is a registered trademark of Linus Torvalds.

Mobile Industry Processor Interface, open membership organization that includes leading companies in the mobile industry that share the objective of defining and promoting open specifications for interfaces inside mobile terminals, see MIPI^® Alliance standard web site https://www.mipi.org

Direct rendering infrastructure (Linux^® framework for allowing direct access to graphics hardware... find more information on official DRI web site http://dri.freedesktop.org/)

Das U-Boot -- the universal boot loader (see U-Boot)