How to Prevent OS Crash on Loss of Power to MIPI Camera?

Issue Overview

Users are encountering an issue with the Jetson Orin Nano Developer Kit running JetPack 5.1.3, where the operating system crashes when power is lost to a MIPI CSI camera while streaming video. The custom V4L2 driver for the camera is functioning correctly during normal operation, but when power is cut and the video stream times out, closing the video application (Guvcview) results in an OS crash. This issue highlights a need for better error handling in the driver to maintain system stability during unexpected power loss.

Relevant Hardware and Software Specifications

• Device: Jetson Orin Nano Developer Kit
• JetPack Version: 5.1.3
• Driver Type: Custom V4L2 driver for MIPI CSI camera
• Applications Used: v4l2-ctl, gstreamer, Guvcview

Symptoms

• OS crashes when closing Guvcview after cutting power to the camera.
• No error handling or logging from the custom driver when power is lost.
• Warnings from tegra-camrtc-capture-vi in kernel logs indicate issues without invoking user-defined error handling code.

Possible Causes

1. Driver Error Handling: The custom driver may not be set up to handle errors related to loss of communication with the camera, leading to system instability.
2. Kernel-Level Issues: Error handling might be occurring at the kernel level rather than within the V4L2 driver, preventing user-defined recovery routines from executing.
3. Power Management Configuration: The system may not be configured to gracefully handle power loss events for connected peripherals.
4. Insufficient Documentation: Lack of examples or documentation on implementing robust error handling in custom drivers may hinder development efforts.

Troubleshooting Steps, Solutions & Fixes

Step-by-Step Instructions

1. Review Driver Code:

   • Check your custom V4L2 driver for proper error handling routines that can manage communication loss with the camera.

2. Inspect Kernel Logs:

   • Use dmesg to examine kernel logs for warnings or errors related to camera communication when power is cut:

     dmesg --follow
     

3. Implement Error Handling:

   • Modify your driver code to include checks for communication status with the camera. Implement recovery logic that allows the driver to reinitialize or reset itself when power is restored.

4. Test with Different Applications:

   • Compare behavior between different applications (e.g., v4l2-ctl vs. Guvcview) to determine if specific software interactions contribute to the crash.

5. Look for Existing Patches or Solutions:

   • Search NVIDIA forums and documentation for patches or solutions related to handling power loss in MIPI cameras.

6. Review Documentation on V4L2 and Error Handling:

   • Consult resources on writing robust V4L2 drivers and proper error handling techniques in Linux kernel modules.

7. Implement Logging:

   • Add logging statements in your driver code to capture events leading up to a crash, which can provide insights into what went wrong.

8. Community Support:

   • Engage with community forums or NVIDIA support for additional guidance on best practices for error handling in custom drivers.

Recommended Fixes

• Implementing robust error handling within the driver code has been suggested as a crucial step toward preventing OS crashes during unexpected power loss.
• Applying any available patches from NVIDIA that address similar issues may also help stabilize operations.

Best Practices for Future Prevention

• Develop comprehensive error handling and recovery mechanisms in all custom drivers to ensure system stability during unexpected events.
• Regularly test hardware configurations under various conditions, including power loss scenarios, to identify potential weaknesses in system design.
• Keep documentation updated regarding modifications made to drivers and configurations for future reference.

Unresolved Aspects and Further Investigation

• Users are still seeking detailed documentation or examples showing effective methods for managing errors related to peripheral communication losses.
• There may be additional kernel-level configurations or patches that could enhance stability but have not yet been identified.

By following these troubleshooting steps and solutions, users can work towards resolving issues related to OS crashes caused by power loss in MIPI cameras connected to their Jetson Orin Nano platform.