Most LCD displays now have embedded touch screen controllers that can be interfaced through I2C or SPI buses. The ConnectCore 8M Nano BSP supports external Goodix capacitive touch controller for the AUO 10.1" LVDS LCD display.

On the ConnectCore 8M Nano Development Kit:

  • Goodix touch controller is connected via the I2C2 port in the LVDS interface at address 0x14. The interrupt line is routed to GPIO4_28 of the i.MX8M Nano CPU.

Kernel configuration

You can manage the Goodix touch controller support through the following kernel configuration option:

  • Goodix I2C touchscreen (CONFIG_TOUCHSCREEN_GOODIX)

This option is enabled as built-in on the default ConnectCore 8M Nano kernel configuration file.

Kernel driver

File Description

drivers/input/touchscreen/goodix.c

Goodix touchscreen driver

Device tree bindings and customization

The Goodix touch screen device tree binding is documented at Documentation/devicetree/bindings/input/touchscreen/goodix.txt

Definition of the Goodix touch screen controller

ConnectCore 8M Nano Development Kit device tree
&i2c2 {

    ...

	goodix_touch: gt9271@14 {
		compatible = "goodix,gt9271";
		reg = <0x14>;
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_touch>;
		/* LVDS interrupt */
		interrupt-parent = <&gpio4>;
		interrupts = <28 IRQ_TYPE_EDGE_FALLING>;
		irq-gpios = <&gpio4 28 GPIO_ACTIVE_LOW>;
		reload-fw-on-resume;
		skip-firmware-request;
		vin-supply = <&reg_5v_board>;
	};

    ...
};