如何使Argon i.MX6UL开发板支持触摸屏？含默认无显示机型适配

Hey there! Let's tackle your two questions about getting touchscreen support working on your Argon i.MX6UL dev board—they're closely related, so I'll break this down into actionable, step-by-step guidance that's easy to follow.

First, let's clarify: the "default no display" issue and touchscreen support share the same core workflow—configuring the display framework and touch driver in your Linux setup. Here's how to fix both:

1. Confirm Hardware Details & Connections #

Before diving into software, get these critical details sorted:

• Screen specs: Note your touchscreen's controller model (e.g., Goodix GT911, FocalTech FT5406 for capacitive; ADS7843 for resistive), resolution (e.g., 800x480), and interface type (I2C/SPI for touch, LCDIF for display). If it's a kit screen, check Argon's official hardware docs; if it's custom, grab the screen datasheet.
• Wiring check: Verify that:
  • LCD data/clock/control lines are connected to the i.MX6UL's LCDIF pins.
  • Touchscreen I2C/SPI lines, interrupt pin, and reset pin are wired to the correct GPIOs (double-check against your board's pinout).

2. Configure the Linux Kernel #

i.MX6UL relies on kernel drivers for display and touch input. Use these steps to enable the right components:

Step A: Enable Kernel Options #

Run make menuconfig in your kernel source directory to open the configuration UI:

• Display support: Navigate to Device Drivers > Graphics support > Frame buffer Devices
  • Enable Freescale i.MX LCD Controller (this is the core display driver for i.MX6UL)
  • Set default screen size or leave it blank (we'll configure exact specs in the device tree later)
• Touchscreen support: Go to Device Drivers > Input device support > Touchscreens
  • Enable the driver matching your touch controller (e.g., Goodix GT911 touchscreen for capacitive, TI ADS7843 touchscreen for resistive)
  • Ensure the corresponding I2C/SPI controller driver is enabled (for I2C, check Device Drivers > I2C support > I2C bus drivers and enable the i.MX6UL I2C controller you're using)

Step B: Modify the Device Tree (Critical!) #

The device tree is how i.MX series boards map hardware to software. Edit your board's DTS file (usually imx6ul-argon.dts) to add display and touch nodes:

Example: Add LCD Display Node (800x480 screen)

&lcdif {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_lcdif_dat &pinctrl_lcdif_ctrl>;
    display = <&display0>;
    status = "okay";

    display0: display {
        bits-per-pixel = <16>;
        bus-width = <18>; /* Adjust to your screen's data bus width (18/24 bits) */
        display-timings {
            native-mode = <&timing0>;
            timing0: timing0 {
                clock-frequency = <33000000>; /* Match your screen's pixel clock (from datasheet) */
                hactive = <800>;
                vactive = <480>;
                hfront-porch = <40>;
                hback-porch = <88>;
                hsync-len = <48>;
                vback-porch = <32>;
                vfront-porch = <11>;
                vsync-len = <1>;
                hsync-active = <0>;
                vsync-active = <0>;
                de-active = <1>;
                pixelclk-active = <0>;
            };
        };
    };
};

/* Add LCD pin control */
&iomuxc {
    pinctrl_lcdif_dat: lcdifdatgrp {
        fsl,pins = <
            MX6UL_PAD_LCD_DATA00__LCDIF_DATA00  0x79
            MX6UL_PAD_LCD_DATA01__LCDIF_DATA01  0x79
            /* Add all data pins up to your bus width (e.g., up to DATA17 for 18-bit) */
            MX6UL_PAD_LCD_DATA17__LCDIF_DATA17  0x79
        >;
    };

    pinctrl_lcdif_ctrl: lcdifctrlgrp {
        fsl,pins = <
            MX6UL_PAD_LCD_CLK__LCDIF_CLK    0x79
            MX6UL_PAD_LCD_ENABLE__LCDIF_ENABLE  0x79
            MX6UL_PAD_LCD_HSYNC__LCDIF_HSYNC    0x79
            MX6UL_PAD_LCD_VSYNC__LCDIF_VSYNC    0x79
        >;
    };
};

Example: Add Touchscreen Node (I2C-connected GT911)

Assuming your touchscreen uses I2C1, with interrupt on GPIO1_IO04 and reset on GPIO1_IO05:

&i2c1 {
    clock-frequency = <400000>;
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_i2c1>;
    status = "okay";

    gt911@5d { /* GT911 I2C address is usually 0x5d or 0x14 */
        compatible = "goodix,gt911";
        reg = <0x5d>;
        interrupt-parent = <&gpio1>;
        interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
        reset-gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
        touchscreen-size-x = <800>;
        touchscreen-size-y = <480>;
        status = "okay";
    };
};

/* Add I2C1 pin control */
&iomuxc {
    pinctrl_i2c1: i2c1grp {
        fsl,pins = <
            MX6UL_PAD_UART2_TX_DATA__I2C1_SCL  0x4001b8b0
            MX6UL_PAD_UART2_RX_DATA__I2C1_SDA  0x4001b8b0
        >;
    };
};

3. Compile & Flash the Kernel/Device Tree #

Once configured, build the kernel and device tree:

# Compile kernel image (use -j with your CPU core count for speed)
make zImage -j$(nproc)

# Compile your board's device tree
make imx6ul-argon.dtb

Flash the generated zImage and imx6ul-argon.dtb to your board's boot partition (or replace the files on your boot TF card if using SD card boot).

4. Test Display & Touch Functionality #

After rebooting your board:

• Test display: Run fbset to check framebuffer specs (should match your screen resolution). If you have a GUI (Qt/X11), you should see the desktop; for command line, try echo "test" > /dev/fb0 to verify basic output.
• Test touch: Use evtest to list input devices, then run evtest /dev/input/eventX (replace X with your touch device number). Touch the screen—you should see coordinate and press/release events. If using a GUI, the cursor should move with your touch.

Quick Note for Your "Default No Display" Kit #

If your new kit doesn't show anything out of the box, it's almost certainly because the default device tree/kernel doesn't have display/touch nodes enabled. Start by grabbing Argon's official BSP (Board Support Package)—it should have pre-configured drivers and device trees for kit components. If your screen isn't covered in the official BSP, use the steps above to customize the setup.

内容的提问来源于stack exchange，提问作者Witco.Fu