Lvds display integration with imx8mp verdin and dahila carrier board

Technical Support
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1

Hello, I am new to this toradex,working with the new imx8M plus SOM, LVDS panel display integration is on going to get prototype alive. Custom embedded Yocto Linux image is the way to go.

  • Yocto reference project fetched from Index of /toradex-manifest.git -b scrathgap-7.x.y -m tdxref/default.xml
  • tdx-reference-minimal-image created ok, and it boots nice, display is not yet connected.
  • Verdin DSI to LVDS adapter will be used to connect custom display, tianma P0840XGF1MA00 panel at this time.

Question : Is P0840XGF1MA00 tianma panel support driver is available?, i have looked into imx8mp.dtsi file to check the default display timings and resolution, but i could not found any relavance regarding display resolution and timings.

The problem is where i could address my display timings and resolution to bring-up my P0840XGF1MA00 tianma (1024*768).

I checked the various queries regarding LVDS integration but i could not able to understand the flow.

Could you Please help me to bring up my LVDS display as i am very new to this yocto and the toradex.

2

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

Did you like my answer?

:+1: :-1:

Hello,

Welcome to the world of Toradex and Yocto! Integrating your Tianma P0840XGF1MA00 LVDS panel with the Verdin iMX8M Plus SOM and Dahlia Carrier Board is an exciting project. Since you’re using a custom Yocto Linux image, configuring the device tree is essential to set up your display correctly.

Here’s a step-by-step guide to help you get started:

  1. Device Tree Configuration: You need to add a node for your LVDS panel in the device tree. This node will specify the display timings and resolution. The panel-lvds driver is suitable for defining these details directly in the device tree.

  2. Specify Display Timings: In the device tree, create a node for your panel under the appropriate LVDS channel. You will need to specify parameters such as hactive, vactive, hsync-len, vsync-len, hfront-porch, vfront-porch, hback-porch, and vback-porch according to your panel’s datasheet.

  3. Data Mapping and Width: Set the fsl,data-mapping and fsl,data-width properties in the lvds-channel node to match the color mapping and depth of your panel. For example, if your panel uses an 18-bit JEIDA format, set these properties accordingly.

  4. Example Configuration:

    &ldb {
    status = "okay";
    lvds-channel@0 {
        fsl,data-mapping = "spwg";
        fsl,data-width = <18>;
        panel@0 {
            compatible = "panel-lvds";
            label = "tianma_p0840xgf1ma00";
            data-mapping = "jeida-18";
            panel-timing {
                clock-frequency = <65000000>;
                hactive = <1024>;
                vactive = <768>;
                hsync-len = <136>;
                hfront-porch = <24>;
                hback-porch = <160>;
                vsync-len = <6>;
                vfront-porch = <3>;
                vback-porch = <29>;
            };
        };
    };
};

  5. Testing and Debugging: Use tools like modetest from the libdrm package to verify the display settings and ensure the panel is correctly initialized.

By following these steps, you should be able to configure your custom LVDS panel with the Verdin iMX8M Plus. Make sure to refer to your panel’s datasheet for accurate timing values and adjust the device tree accordingly.

If you have any more questions or need further assistance, feel free to ask. Enjoy your journey with Toradex!

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

Installing Display driver on Verdin iMX8M Mini.

5

Hi @premsai ,
From where are you following the steps to compile device tree overlay?
The error you are getting is related to toolchain or dtc not available plus the syntax error.
You need to make sure that the device tree overlay is build against a kernel .

eg, before make command, check out the kernel againts which you are compiling dtbo
export STAGING_KERNEL_DIR=/home/user/workdir/linux-toradex

Below article could be helpful
Build device tree overlay from source

6

Thanks @sahil.tx
Now i able to build the overlays.
But we are using the custom board, i want to change the pinctrl according to our board to up the display.
could you please provide the information to configure this.

Thanks in advance.

10

Hi @premsai ,
What do you mean by “change the pinctrl”?
Do you mean you want to set the display timings in the device tree or are you using some other pins for your display?
Did you also check if these pins are compatible from the datasheet?

11

Hi @sahil.tx , Thanks for you reply
Actually we are using native lvds not dsi to lvds interface.
I was able to bring up my display but the issue is screen is not clear even if my qt app is showing 60fps. The image i have shared below.

20241227_165100~2
20241227_165100~21920×2555 331 KB

And the overlay i have passed is uploaded below.
native-lvds-custom_overlay.dts (2.6 KB)
I reference dts i have used is verdin-imx8mp_panel-cap-touch-10inch-lvds_overlay.dts

The datasheet timings of my tianma display is shared below.
Tianma_LVDS_Display.pdf (1.2 MB)

Please help me to fix this issue.
Thanks in advance.

13

Hi @sahil.tx ,
The issue got resolve by changing the data-mapping from spwg to jeida.

14

Hi @premsai,
Nice to hear that you were able to solve the issue :slight_smile: