Not getting desired clock frequency in dual-lvds mode

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Based on the context provided, it seems like you are experiencing issues with setting the correct clock frequency for a dual LVDS display using the SN65DSI84 chip on a Verdin iMX8MP SoM. The problem arises when trying to achieve the desired 146MHz frequency in dual LVDS mode, which results in a black screen, while a lower frequency range (95.57 MHz to 99.20 MHz) works but is not optimal.

Here are a few suggestions to troubleshoot and potentially resolve the issue:

  1. Check SN65DSI84 Configuration: Ensure that the SN65DSI84 chip is correctly configured for dual LVDS mode. This includes verifying the register settings for the chip, as incorrect settings could prevent the chip from outputting the desired frequency.

  2. Device Tree Configuration: Double-check the device tree configuration to ensure that all necessary properties for dual LVDS mode are correctly set. This includes ensuring that the dual-lvds-odd-pixels and dual-lvds-even-pixels properties are correctly defined and that the endpoints are properly linked.

  3. Clock Source and PLL Settings: Investigate the clock source and PLL settings for the SN65DSI84. The issue might be related to how the clock is being generated or divided. Ensure that the PLL is correctly configured to output the desired frequency.

  4. Signal Integrity: Consider the possibility of signal integrity issues on the custom adapter board. Ensure that the traces are properly designed for high-frequency signals and that there is adequate termination to prevent reflections.

  5. Consult SN65DSI84 Datasheet: Review the SN65DSI84 datasheet for any specific requirements or limitations regarding dual LVDS operation and clock frequencies.

  6. Kernel and Driver Support: Ensure that the kernel and driver versions you are using fully support the SN65DSI84 and the dual LVDS configuration. There might be patches or updates available that address similar issues.

If these suggestions do not resolve the issue, it may be beneficial to reach out to Toradex technical support for further assistance, as they can provide more specific guidance based on your hardware setup and configuration.

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

LVDS dual channel configuration using device tree overlay on Torizoncore (Apalis iMX6/ Apalis eval board).