DP Compliance TX_PULL Enable Issue on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users are experiencing difficulties in enabling the TX_PULL feature for DisplayPort (DP) compliance on the Nvidia Jetson Orin Nano Dev board. The specific symptoms include:

• Register Values: Users report that the register value at address 0x1380c130 does not reflect the expected values (0x400200 or 0x400206) after attempting to set the TX_PULL value using the dcb_tool. Instead, it consistently reads as 0x206 regardless of modifications made to the dcb file.
• Context of Issue: This problem arises during attempts to configure the DP settings for a 4K@30 panel, particularly when users are trying to set the TX_PULL value in the device tree configuration file (dtsi) using dcb_tool.
• Hardware and Software Specifications: The issue is reported with the Jetson Orin Nano Dev board, specifically with the tegra234-dcb-p3767-0000-dp.dtsi file. Users are advised to use dcb_tool from BSP 36.
• Frequency: This issue appears to be consistent across multiple attempts and users, indicating a potential systemic problem.
• Impact: The inability to modify the TX_PULL setting effectively hampers compliance testing, which could affect project timelines and functionality.

Possible Causes

Several potential causes for this issue have been identified:

• Hardware Incompatibilities: There may be inherent limitations or defects in specific carrier boards that prevent proper communication with the DP interface.
• Software Bugs or Conflicts: The dcb_tool may have bugs that prevent it from correctly applying changes to the dtsi file.
• Configuration Errors: Users may not be modifying the correct properties within the dtsi file or may not fully understand how to apply changes correctly.
• Driver Issues: The driver responsible for handling DP settings might not be utilizing the modified dcb image correctly.
• Environmental Factors: Power supply inconsistencies or thermal issues could potentially affect device performance.
• User Errors: Misconfigurations during the flashing process or incorrect usage of tools like dcb_tool could lead to these issues.

Troubleshooting Steps, Solutions & Fixes

To address this issue, users can follow these troubleshooting steps and solutions:

1. Verify Tool Version:

   • Ensure you are using dcb_tool from BSP 36. Older versions may not support necessary features.

2. Modify dtsi File Correctly:

   • Use dcb_tool to modify the dtsi file:

     $ dcb_tool -m tegra234-dcb-p3767-0000-dp.dtsi
     

   • Follow prompts to navigate and modify settings related to SOR TX Pull-Up (TX PU).

3. Full Flash Required:

   • After modifying the dtsi file, ensure you perform a full flash of your device:

     sudo ./flash.sh jetson-orin-nano-devkit-qspi mmcblk1p1
     

   • Confirm that you are using the correct target for flashing.

4. Check Bootloader Files:

   • Make sure that your bootloader includes the updated dcb image. Sometimes, older dtb files can prevent new configurations from being applied.

5. Testing Different Values:

   • Experiment with various values for TX PU (e.g., 0x1, 0xa, etc.) and observe if any changes occur in register readings.

6. Driver Verification:

   • Check if the driver is correctly utilizing the modified dcb image. This may require additional debugging or logging.

7. Consult Documentation:

   • Refer to official Nvidia documentation for any updates regarding driver compatibility and known issues with DP compliance.

8. Community Support:

   • Engage with community forums for shared experiences and solutions. Other users may have encountered similar issues and found effective workarounds.

9. Log Exporting:

   • If issues persist, utilize tools within SDK Manager to export logs and share them on forums for further assistance.

10. Best Practices for Future Configuration:

    • Always back up original configuration files before making changes.
    • Document each step taken during configuration changes for easier troubleshooting in future attempts.

By following these steps, users should be able to diagnose and potentially resolve issues related to enabling TX_PULL compliance on their Nvidia Jetson Orin Nano Dev boards.