HDMI Display Signal Issue on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users of the Nvidia Jetson Orin Nano Dev Board have reported an issue where the HDMI display does not receive a signal when connected after the system has booted. The symptoms include:

• No signal on the HDMI display after booting, despite the display functioning correctly when connected before startup.
• Users must manually restart the display manager using the command systemctl restart gdm to restore functionality.
• The command xrandr is executed but does not provide useful status information regarding the HDMI connection.

The problem occurs in the context of using Jetson Linux SDK version 36.3 on a custom board built around the Orin Nano. Users have noted that they cannot find a status file for HDMI in the /sys/class/drm/ directory, which would typically indicate whether an HDMI device is connected.

The issue appears to be consistent across multiple attempts, significantly impacting user experience by requiring manual intervention to restore display functionality.

Possible Causes

Several potential causes for this issue have been identified:

• Hardware Incompatibilities or Defects: There may be issues with the custom board design or components that affect HDMI functionality.

• Software Bugs or Conflicts: There could be bugs in the Jetson Linux SDK or conflicts with other installed software that prevent proper detection of HDMI connections.

• Configuration Errors: Incorrect settings in the device tree or pin multiplexing configurations may lead to failure in recognizing HDMI hotplug events.

• Driver Issues: Outdated or improperly configured drivers may not support hotplug functionality for HDMI.

• Environmental Factors: Power supply issues or temperature extremes could affect hardware performance and signal integrity.

• User Errors or Misconfigurations: Incorrectly set parameters in the device tree or GPIO configurations might lead to this issue.

Troubleshooting Steps, Solutions & Fixes

To resolve the HDMI display signal issue, users can follow these troubleshooting steps and potential solutions:

1. Check Device Tree Configuration:

   • Ensure that the High-Priority Data (HPD) GPIO configuration is included in the device tree. Refer to p3509-a02-p3767-0000.conf for HDMI-related settings.
   • Verify that tegra234-dcb-p3767-0000-hdmi.dtbo is correctly referenced in your device tree files.

2. Inspect GPIO Status:

   • Use a multimeter or probe to check the HPD pin status. Confirm that it changes when an HDMI display is plugged in.
   • If using an open-drain level-shifting chip externally, ensure that pull-up configurations are correctly set in the device tree.

3. Review Logs for Errors:

   • Check /var/log/Xorg.0.log and other relevant logs for any errors related to HDMI detection during hotplug events.
   • Look for any discrepancies in logs when plugging and unplugging the HDMI cable.

4. Reflash with Default BSP Configuration:

   • If modifications have been made to the board support package (BSP), consider reflashing with default configurations (p3509+p3767) to eliminate custom changes as a source of error.

5. Test with Different Hardware:

   • If possible, test with another HDMI display or cable to rule out hardware defects.
   • Try using a different power supply to ensure adequate power delivery.

6. Update Drivers and Firmware:

   • Ensure that all drivers and firmware are up-to-date, as updates may include fixes for known issues related to HDMI functionality.

7. Consult Documentation:

   • Review Nvidia’s official documentation regarding HDMI setup on Jetson devices for any additional configuration steps that may be necessary.

8. Best Practices for Future Prevention:

   • Always connect displays before powering on the system.
   • Regularly check for updates to both software and hardware configurations.

By following these steps, users should be able to diagnose and potentially resolve issues related to HDMI connectivity on their Nvidia Jetson Orin Nano Dev Board. If problems persist, further investigation into hardware design and compatibility may be necessary.