Changing clock frequency for display with Verdin IM8MX Plus

Technical Support
1

Verdin IM8MX Plus
Custon Toradex designed Carrier board

We need to change the pixel clock frequency for a 5" display in the Toradex software. We are having a difficult time making this change. 5" displays require a considerably lower clock frequency than 7" or 10". Has anyone acheived this?

2

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Hello! Thank you for reaching out.

To set a custom pixel clock frequency for your 5" display on the Verdin iMX8M Plus with Torizon (or Linux), you need to update the display’s timing parameters using a device tree overlay. The device tree handles hardware configuration at boot, including display timings like pixel clock.

Here’s how you can proceed:

1. Gather Display Timing Information

First, obtain your 5" display’s required timing parameters:

  • Pixel clock frequency (in Hz)
  • Horizontal/vertical active pixels and sync parameters
  • Sync pulse, back porch, front porch values

These should be provided in the display’s datasheet.

2. Create or Edit a Device Tree Overlay

Identify the node in the Toradex-provided device tree that matches your display interface (e.g., LVDS, DSI, RGB).

Example (for an LVDS panel):

&lcdif {
    status = "okay";
    display-timings {
        native-mode = <&timing_x>;
        timing_x: timing_x {
            clock-frequency = <your_pixel_clock>;
            hactive = <...>;
            vactive = <...>;
            hfront-porch = <...>;
            hback-porch = <...>;
            hsync-len = <...>;
            vfront-porch = <...>;
            vback-porch = <...>;
            vsync-len = <...>;
            // Add other parameters as needed.
        };
    };
};

Replace <your_pixel_clock> and the display timing values with those for your 5" display.

3. Deploy and Test

  • Add your custom overlay to /boot/overlays and list it in the overlays.txt on the boot partition if using TorizonCore.
  • Reboot your system. The driver should now initialize the pixel clock and timings according to your new parameters.

References:

If you share your existing overlay or the timing parameters you’re trying to use, I can help refine the syntax further.

Best regards, Toradex AI Assistant.

3

Could you please specify which iMX8M Plus display interface you are talking about (MIPI DSI, HDMI, LVDS)?