Custom LVDS display interface with IRIS carrier board over iMX7d 1GB

Technical Support
1

Dear Toradex Community,

I’m having a custom toradex iris carrier board equipped with iMX7d 1GB. as per the reference schematic, we’ve took the same reference on my board. i’m using custom LVDS display of make AUO with model name G101EVT03.0. i’ve created new dts file for the lvds, compiled it and deployed under /boot/overlays.txt . my system is able to boot successfully but display not showing anything even backlight is still OFF. Kindly review these points and let me know what can be done next.

2

Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

I’d be glad to help you troubleshoot your custom LVDS display setup! To provide the most accurate guidance, could you please specify which OS and version you are running on your Colibri iMX7D 1GB module?

For example:

  • Hardware: Colibri iMX7D 1GB with Iris Carrier Board
  • OS: Torizon OS 7.x.y, BSP 6.x.y, or Yocto-based BSP
  • Version: The exact version number

You can get this information by running the tdx-info command on your device. More details about this command are available at: Getting Device Information with Tdx-Info | Toradex Developer Center

Initial Troubleshooting Points

Based on the available documentation, here are some key areas to verify for LVDS display integration:

1. Device Tree Overlay Compatibility

For Colibri iMX7, the LVDS signal is provided through an RGB to LVDS transmitter on the Iris carrier board (1). The LVDS cable that comes with standard Toradex displays is compatible with Iris V2.0 onward (1).

2. Backlight Configuration

Since your backlight is not turning on, this is likely a critical issue. The backlight configuration needs to be properly defined in your device tree overlay, including:

  • Backlight enable GPIO configuration
  • PWM configuration for brightness control
  • Power supply definitions

3. Display Timing Parameters

Your custom AUO G101EVT03.0 display will require specific timing parameters that must match the display’s datasheet specifications.

Once you provide the OS version information, I can give you more specific guidance on:

  • The correct overlay structure for your platform
  • Proper backlight configuration syntax
  • Display timing parameter format
  • Debugging steps specific to your OS version

Common platforms to consider:

  • OS: Torizon OS 6.x.y, Torizon OS 7.x.y, BSP 6.x.y, BSP 7.x.y
  • Integration: Device tree overlays, LVDS configuration, backlight control

Best regards, Toradex AI Assistant.

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If I answered your question, please tick the “Solution” checkbox.

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3

Dear Team,

DO find my tdx-info below:

root@colibri-imx7-emmc-15537390:~# tdx-info

Software summary

Bootloader: U-Boot
Kernel version: 6.1.123-6.8.1-devel+git.7dc732d24ff7 #1 SMP Thu Jan 2 09:30:56 UTC 2025
Kernel command line: root=PARTUUID=ea6453a9-02 ro rootwait console=tty1 console=ttymxc0,115200n8 consoleblank=0
Distro name: NAME=“TDX Wayland with XWayland Upstream”
Distro version: VERSION_ID=6.8.1-devel-20250526150338-build.0
Distro variant: -
Hostname: colibri-imx7-emmc-15537390

Hardware info

HW model: Toradex Colibri iMX7D 1GB (eMMC) on Colibri Evaluation Board V3
Toradex version: 0039 V1.1B
Serial number: 15537390
Processor arch: armv7l

root@colibri-imx7-emmc-15537390:~#

4

Thank you for providing the system information! I can see you’re running TDX Wayland with XWayland Upstream version 6.8.1-devel on a Colibri iMX7D 1GB (eMMC) with the Evaluation Board V3.

LVDS Display Configuration for Colibri iMX7

Based on your setup, here’s what you need to know about LVDS display configuration:

Available Overlays for Colibri iMX7

For the Colibri iMX7 module with BSP 6.0-6.5, the following display overlays are available (1):

  • LVDS Capacitive Touch Display 10.1": colibri-imx7_panel-cap-touch-10inch-lvds_overlay.dtbo (1)
  • Parallel RGB displays: Various 7" touch displays (1)
  • VGA output: colibri-imx7_vga-640x480_overlay.dtbo (1)

Key Configuration Points

  1. LVDS Signal Path: The LVDS signal is provided through an RGB to LVDS transmitter on the carrier board (1)

  2. Overlay Structure: For custom displays, you’ll need to create a device tree overlay similar to the existing ones but with your AUO G101EVT03.0 specifications (2)

  3. Required Components: Your custom overlay should include:

    • Display timing parameters specific to your AUO panel
    • Backlight configuration (GPIO and PWM settings)
    • Panel power supply definitions
    • Touch controller configuration (if applicable)

Troubleshooting Steps

Since your backlight is not turning on, check these critical areas:

  1. Backlight GPIO Configuration: Ensure the backlight enable GPIO is properly configured in your device tree overlay (2)

  2. PWM Configuration: Verify the PWM channel for backlight brightness control is correctly set up (2)

  3. Overlay Application: Check if your overlay was applied successfully by examining /proc/device-tree/chosen/overlays/ (2)

# ls /proc/device-tree/chosen/overlays/
# cat /proc/device-tree/chosen/overlays/your_custom_overlay.dtbo

(2)

If the value shows 0, the overlay was applied successfully (2)

  1. Display Timing Parameters: Ensure your custom overlay includes the correct timing parameters from the AUO G101EVT03.0 datasheet (2)

Next Steps

To help you further, could you share:

  • Your custom device tree overlay source code
  • The exact error messages or kernel logs related to display initialization
  • Whether you’ve verified the hardware connections match the Iris carrier board LVDS pinout

The most recommended way to create a new overlay is to start with a similar overlay and adapt it to your project’s needs (2).

Best regards, Toradex AI Assistant.

Did you like my answer? :+1: :-1:

If I answered your question, please tick the “Solution” checkbox.

For follow-up questions to me, please use @ToradexAI in your post.

5

Dear Team,

I’ve verify the LVDS display connections with Iris carrier board and seems ok.

Do find my .dts file below:

// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
/*

  • AUO G101EVT03.0 10.1" LVDS (1280x800) for Colibri iMX7D on Iris V2 Carrier Board
  • Based on Toradex colibri-imx7_panel-cap-touch-10inch-lvds overlay structure.
  • Signal path: iMX7D eLCDIF → 18-bit parallel RGB (bgr666) → DS90C363B → LVDS → AUO panel
  • Use INSTEAD of colibri-imx7_panel-cap-touch-10inch-lvds_overlay.dtbo (not alongside it).
    */

/dts-v1/;
/plugin/;

/ {
compatible = “toradex,colibri-imx7d\0toradex,colibri-imx7s\0toradex,colibri-imx7d-emmc”;
};

/* Enable backlight */
&backlight {
status = “okay”;
};

/* Disable CAN bus - shares pins with LVDS transceiver GPIOs */
&flexcan1 {
status = “disabled”;
};

/* LVDS_COLOR_MAP: output-low = 18-bit mode (DS90C363B) */
&gpio2 {
lvds-color-map {
gpio-hog;
gpios = <0x0d 0x00>;
line-name = “LVDS_COLOR_MAP”;
output-low;
};
};

/* LVDS transceiver control GPIOs */
&gpio7 {
lvds-ch-mode {
gpio-hog;
gpios = <0x03 0x00>;
line-name = “LVDS_CH_MODE”;
output-high;
};

lvds-pwron {
	gpio-hog;
	gpios = <0x0b 0x00>;
	line-name = "LVDS_PWRON";
	output-high;
};

lvds-rgb-mode {
	gpio-hog;
	gpios = <0x02 0x00>;
	line-name = "LVDS_RGB_MODE";
	output-low;
};

};

/* Enable LCD interface */
&lcdif {
status = “okay”;
};

/* Configure panel-dpi: data-mapping and pinctrl */
&panel_dpi {
data-mapping = “bgr666”;
pinctrl-names = “default”;
pinctrl-0 = <&pinctrl_lvds_transceiver>;
status = “okay”;

/* AUO G101EVT03.0 panel settings */
compatible = "panel-dpi";
width-mm = <217>;
height-mm = <136>;

panel-timing {
	clock-frequency = <83000000>;  /* Request 83 MHz; PLL achieves 82.075 MHz (in AUO range) */
	hactive = <1280>;
	hback-porch = <80>;
	hfront-porch = <48>;
	hsync-len = <32>;
	vactive = <800>;
	vback-porch = <15>;
	vfront-porch = <3>;
	vsync-len = <6>;
	de-active = <1>;
	hsync-active = <0>;
	vsync-active = <0>;
	pixelclk-active = <0>;
};

};

/* Enable PWM for backlight */
&pwm1 {
status = “okay”;
};

Kindly check this and let me know any modifications

6

Dear Team,

Awaiting for your reply on this.

7

Hi @Design-Team-ATPL ,
Keeping in mind that the IRIS 2.0 provides dual channel LVDS transmitter and the display is a single channel display, I would suggest you to modify device tree using overlay –> colibri-imx7_panel-cap-touch-10inch-lvds_overlay.dts
3 dtsi files are included and you can use that to modify the settings according to your display.
eg , add your timings here display-dpi-lt170410_overlay.dtsi

8

Dear Team,

Thanks for the response. As per the provided inputs, I’ve added all things in one single file. Kindly find the below .dts for the reference. let me know about this as will it work or not or do i need to make any modification:

/dts-v1/;
/plugin/;

/ {
compatible = “toradex,colibri-imx7d”,
“toradex,colibri-imx7s”,
“toradex,colibri-imx7d-emmc”;

fragment@0 {
    target = <&backlight>;
    __overlay__ {
        status = "okay";
    };
};

fragment@1 {
    target = <&flexcan1>;
    __overlay__ {
        status = "disabled";
    };
};

fragment@2 {
    target = <&gpio2>;
    __overlay__ {
        lvds-color-map {
            gpio-hog;
            gpios = <13 1>; /* SODIMM 95, active high */
            line-name = "LVDS_COLOR_MAP";
            output-low;
        };
    };
};

fragment@3 {
    target = <&gpio7>;
    __overlay__ {
        lvds-ch-mode {
            gpio-hog;
            gpios = <3 1>; /* SODIMM 55, active high */
            line-name = "LVDS_CH_MODE";
            output-high;
        };

        lvds-pwron {
            gpio-hog;
            gpios = <11 1>; /* SODIMM 99, active high */
            line-name = "LVDS_PWRON";
            output-high;
        };

        lvds-rgb-mode {
            gpio-hog;
            gpios = <2 1>; /* SODIMM 63, active high */
            line-name = "LVDS_RGB_MODE";
            output-low;
        };
    };
};

fragment@4 {
    target = <&lcdif>;
    __overlay__ {
        status = "okay";
    };
};

fragment@5 {
    target = <&panel_dpi>;
    __overlay__ {
        data-mapping = "bgr666";
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_lvds_transceiver>;
        status = "okay";

        /* AUO G101EVT03.0 panel settings */
        compatible = "panel-dpi";
        width-mm = <217>;
        height-mm = <136>;

            panel-timing {
            clock-frequency = <69000000>;

            hactive = <1280>;
            hfront-porch = <48>;
            hback-porch = <80>;
            hsync-len = <48>;

            vactive = <800>;
            vfront-porch = <3>;
            vback-porch = <10>;
            vsync-len = <3>;

            hsync-active = <0>;
            vsync-active = <0>;
            de-active = <1>;
            pixelclk-active = <0>;
        };
    };
};

fragment@6 {
    target = <&pwm1>;
    __overlay__ {
        status = "okay";
    };
};

};

9

Hi @Design-Team-ATPL
What I meant is that you need to re-compile this overlay –> colibri-imx7_panel-cap-touch-10inch-lvds_overlay.dts
This overlay includes below 3 files
#include "colibri-imx7_atmel-mxt-connector_overlay.dtsi" #include "colibri-imx7_parallel-rgb-lvds-rgb24-single_overlay.dtsi" #include "display-dpi-lt170410_overlay.dtsi"

So, you can modify you display settings in these 3 files, eg you can add your timing parameters in “display-dpi-lt170410_overlay.dtsi“ and other related settings in the other files