Jetson Orin Nano GTE Configuration Issues

Issue Overview

Users are experiencing difficulties enabling the Generic Timestamping Engine (GTE) on the Nvidia Jetson Orin Nano Developer Kit. The main symptoms include:

• Inability to see /dev/gtechip0 after rebooting, indicating that the GTE is not functioning.
• Confusion regarding the configuration of AON GPIO pins, as users report that these pins are not enabled by default.
• The issue occurs during the setup phase, specifically after modifying device tree source files and kernel configurations.

The affected hardware includes the Jetson Orin Nano Developer Kit, with software specifications involving modifications to the device tree files (tegra234-p3767-0000-p3768-0000-a0.dts and tegra234-p3768-0000-a0.dtsi). Users have reported inconsistent success in getting GTE to work, which affects their ability to accurately time interrupts from an IMU.

Possible Causes

Several potential causes for the issue have been identified:

• Hardware Incompatibilities: Incorrect or incompatible GPIO configurations may lead to issues with GTE functionality.
• Software Bugs: There may be bugs in the Jetson Linux distribution that affect GTE operation.
• Configuration Errors: Misconfiguration in device tree files could prevent proper initialization of GTE.
• Driver Issues: Missing or outdated drivers might result in /dev/gtechip0 not being created.
• User Errors: Incorrect modifications made by users in the device tree or kernel configuration may lead to failures in enabling GTE.
• Environmental Factors: Power supply issues or overheating could potentially impact performance.

Troubleshooting Steps, Solutions & Fixes

To address the issues with enabling GTE on the Jetson Orin Nano Developer Kit, follow these troubleshooting steps and potential solutions:

1. Verify Device Tree Modifications:

   • Ensure that you have correctly added the following lines to tegra234-p3768-0000-a0.dtsi:

     gte@3aa0000 {
         status = "okay";
     };
     gte@c1e0000 {
         status = "okay";
     };
     gpio@c2f0000 {
         /delete-property/ use-timestamp;
     };
     

2. Rebuild and Flash Kernel and Device Tree:

   • After making changes, rebuild the kernel image and device tree blob. Use the following commands:

     make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
     

   • Flash the new images to your Jetson board and update /boot/extlinux/extlinux.conf accordingly.

3. Check Kernel Configuration:

   • Ensure that your kernel configuration includes:

     CONFIG_TEGRA_GTE_TEST=m
     CONFIG_TEGRA_HTS_GTE=y
     

4. Use SDK Manager for Flashing:

   • If issues persist, consider using NVIDIA SDK Manager for a complete flash of your Jetson board. Make sure to put the board into recovery mode by connecting pins 9 and 10 while powering on.

5. Testing GPIO Configuration:

   • To configure AON GPIO pins, refer to documentation on how to enable these pins using tools like jetson-io.py. Run:

     sudo /opt/nvidia/jetson-io/jetson-io.py
     

   • Select "Configure Jetson 40 Pin Header" and enable AON GPIO options as needed.

6. Consult Documentation:

   • Refer to the Generic Timestamp Engine — Jetson Linux Developer Guide for detailed instructions on configuring GTE.

7. Community Support:

   • If further assistance is needed, consider reaching out on forums or community channels for specific advice related to your configuration.

8. Best Practices for Future Prevention:

   • Always back up original device tree files before making modifications.
   • Document changes made during configuration for easier troubleshooting in the future.

By following these steps, users should be able to diagnose and resolve issues related to enabling the Generic Timestamping Engine on their Jetson Orin Nano Developer Kit.