CSI Skew Calibration Issues on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users of the Nvidia Jetson Orin Nano Dev board have reported issues related to CSI (Camera Serial Interface) skew calibration when operating at data rates exceeding 1.5 Gbps. The main symptoms include:

• Stalling of the receiver: If the deskew signal is not sent by the sensor or deserializer, the receiver stalls and the capture process times out.
• Inconsistent behavior with extra calibration sequences: Users have queried whether the Orin Nano can utilize additional skew calibration sequences sent after each frame, beyond the mandatory initialization sequence.

The issue primarily occurs during setup and operation of high-bandwidth camera systems, particularly when using a TI TDES954 deserializer configured for 1.6 Gbps per lane. Users have noted that while the initial skew calibration sequence is successfully utilized, there is uncertainty regarding the effectiveness or necessity of periodic skew calibration sequences.

The frequency of this issue appears to be consistent among users operating at high data rates, impacting their ability to effectively utilize camera systems with the Orin Nano.

Possible Causes

Several potential causes for these issues have been identified:

• Hardware Incompatibilities: The specific deserializer chipset (TI TDES954) may not fully align with the capabilities of the Orin Nano regarding skew calibration.

• Firmware Limitations: The RCE (Real-Time Computer Engine) firmware currently only supports initial skew calibration sequences and does not accommodate periodic calibration sequences, which may lead to confusion among users.

• Configuration Errors: Incorrect settings in the device tree source (DTS) files or misconfigurations related to CSI settings could lead to improper operation.

• Driver Issues: Outdated or incompatible drivers may hinder proper communication between the Orin Nano and connected hardware.

• User Misconfigurations: Users may inadvertently misconfigure their setups, leading to improper handling of skew calibration signals.

Troubleshooting Steps, Solutions & Fixes

To address these issues effectively, users can follow these troubleshooting steps and solutions:

1. Verify Hardware Configuration:

   • Ensure that all hardware components are compatible and correctly connected.
   • Check that the TI TDES954 deserializer is configured to send the initial skew calibration sequence.

2. Check Device Tree Settings:

   • Confirm that the DTS settings for pixel clock value are correctly configured to enable skew calibration.
   • Example configuration in DTS:

     CSI_CAL_EN: Enable initial CSI Skew-Calibration sequence
     

3. Monitor Deskew Signals:

   • Use an oscilloscope to validate that the deskew signals are being sent by the sensor/deserializer as expected.
   • Ensure that no additional signals are interfering with communication.

4. Update Firmware and Drivers:

   • Check for any available firmware updates related to RCE that might improve handling of skew calibration.
   • Update drivers for both the Orin Nano and any connected peripherals.

5. Test with Different Configurations:

   • Experiment with different configurations by enabling/disabling periodic skew calibration sequences to observe any changes in behavior.
   • Note that current firmware does not support periodic sequences; thus, focus should remain on initial sequences.

6. Consult Documentation:

   • Refer to L4T (Linux for Tegra) documentation for any specific instructions regarding CSI setup and skew calibration.
   • Review any bug fixes or patches mentioned in related topics within forums.

7. Best Practices for Future Prevention:

   • Regularly check for updates from Nvidia regarding firmware and driver releases.
   • Maintain a log of configurations used in successful setups for future reference.

8. Community Engagement:

   • Engage with community forums for shared experiences and solutions from other users facing similar issues.
   • Consider posting detailed questions if further clarification is needed on specific aspects of CSI skew calibration implementation.

By following these steps, users can diagnose and potentially resolve issues related to CSI skew calibration on their Nvidia Jetson Orin Nano Dev boards.