Modifying Device Tree on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users of the Nvidia Jetson Orin Nano development board are experiencing difficulties in modifying the device tree. The main challenges include:

• Identifying the correct file to modify in the device tree
• Locating the device tree file within the downloaded source code
• Understanding the process of modifying and rebuilding the device tree
• Navigating the complexities of the Jetson Linux development environment

This issue primarily affects users during the setup and customization phase of their Jetson Orin Nano projects, impacting their ability to make hardware-specific adjustments.

Possible Causes

1. Lack of familiarity with Jetson Linux environment: Users, especially novices, may struggle with the specific file structure and development processes of Jetson Linux.

2. Insufficient documentation: The steps for modifying the device tree may not be clearly outlined in readily available documentation.

3. Version-specific differences: Different versions of Jetson Linux (e.g., R36.2 vs R36.3) may have slight variations in their file structures or processes.

4. Complexity of the Jetson ecosystem: The interplay between kernel, device tree, and bootloader in the Jetson ecosystem can be complex for newcomers.

Troubleshooting Steps, Solutions & Fixes

1. Use the correct Jetson Linux version

   • It is recommended to use Jetson Linux R36.3.0 instead of R36.2, as the latter is a Developer Preview release.

2. Set up the development environment

   • Follow the Quick Start guide in the NVIDIA Jetson Linux Developer Guide to set up your host PC and flash the devkit.
   • Download the kernel and rootfs files from the Jetson Linux 36.3 page on the NVIDIA Developer website.

3. Identify the correct device tree file

   • Flash your board and check the flashing logs to identify the device tree file in use.
   • In the provided example, the device tree file was identified as tegra234-p3768-0000+p3767-0004-nv.dts.

4. Locate the device tree file

   • Navigate to the appropriate directory in the downloaded source code to find the .dts file identified in the previous step.

5. Modify the device tree

   • Open the identified .dts file in a text editor.
   • Make the necessary modifications to add your custom nodes or make other changes.

6. Rebuild the kernel and device tree

   • After modifying the device tree, rebuild the kernel using the following command:

     make -C kernel
     

   • However, this step alone may not be sufficient. Refer to the official documentation for a complete rebuild process.

7. Follow official documentation for kernel customization

   • For a comprehensive guide on kernel customization, including device tree modifications, refer to the official NVIDIA documentation:
     https://docs.nvidia.com/jetson/archives/r36.3/DeveloperGuide/SD/Kernel.html

8. Flash the updated kernel and device tree

   • After rebuilding, flash your Jetson Orin Nano with the updated kernel and device tree.
   • Use the following command for flashing:

     sudo ./tools/kernel_flash/l4t_initrd_flash.sh --external-device nvme0n1p1 -c tools/kernel_flash/flash_l4t_external.xml -p "-c bootloader/generic/cfg/flash_t234_qspi.xml" --showlogs --network usb0 jetson-orin-nano-devkit internal
     

9. Verify changes

   • After flashing, boot your Jetson Orin Nano and verify that your device tree modifications have been applied correctly.

10. Troubleshooting tips

    • Always keep a backup of original files before making modifications.
    • If issues persist, consider reverting to the original device tree and making incremental changes to isolate the problem.
    • Consult the Jetson community forums or NVIDIA support for specific issues not covered in the documentation.