Writing a Camera Sensor Driver for MIPI CSI Transceiver on Nvidia Jetson Platform

Issue Overview

Users are seeking guidance on developing a camera sensor driver for a new MIPI CSI transceiver on the Nvidia Jetson platform. The main points of discussion include:

• The possibility of using plain V4L2 without Tegracam add-ons
• Implementing a camera driver without I2C and camera controls
• Configuring frame parameters (resolution, framerate) independently of the Device Tree
• Passing configuration values as parameters when loading the kernel module

The issue impacts developers working on custom camera implementations for the Jetson platform, particularly those requiring flexibility in image size and framerate configurations.

Possible Causes

1. Limited documentation: Lack of clear guidelines for implementing custom camera drivers on the Jetson platform.
2. Platform-specific requirements: Nvidia Jetson may have specific requirements for camera driver implementation that are not immediately apparent.
3. Tegracam dependency: The platform might be optimized for use with Tegracam, making alternative implementations challenging.
4. Device Tree limitations: The default configuration method using Device Tree may not provide the desired flexibility for dynamic parameter changes.

Troubleshooting Steps, Solutions & Fixes

1. Use Tegracam for CSI camera implementation

   • It is recommended to implement the sensor driver based on Tegracam for CSI cameras on the Nvidia Jetson platform.
   • While it’s possible to use standard V4L2 functions, Tegracam is designed to work optimally with the Jetson ecosystem.

2. Modify existing reference drivers

   • Use reference drivers like imx219 or imx477 as a starting point.
   • Remove I2C register access and replace camera control functions with dummy functions to create a basic CSI data grabbing driver.

3. Implement custom frame parameter configuration

   • Define sensor modes directly in the sensor kernel driver instead of relying on the Device Tree.
   • This approach allows for more flexibility in handling different image sizes and framerates.
   • Example modification in the sensor driver:

   static struct sensor_mode_properties sensor_modes[] = {
       {
           .image_width = 1920,
           .image_height = 1080,
           .framerate = 30,
           // Other necessary properties
       },
       // Add more modes as needed
   };
   

4. Implement module parameters for dynamic configuration

   • Use module parameters to allow passing configuration values when loading the kernel module.
   • Example implementation:

   static int image_width = 1920;
   static int image_height = 1080;
   static int framerate = 30;
   
   module_param(image_width, int, 0644);
   module_param(image_height, int, 0644);
   module_param(framerate, int, 0644);
   
   static int sensor_probe(struct i2c_client *client,
                           const struct i2c_device_id *id)
   {
       // Use image_width, image_height, and framerate to configure the sensor
       // instead of reading from Device Tree
   }
   

5. Consider Argus compatibility

   • If Argus applications are not required, you can define sensor modes only in the kernel driver without using the Device Tree.
   • This provides more flexibility but may limit compatibility with some Nvidia ecosystem tools.

6. Consult Nvidia Developer Resources

   • Refer to the Nvidia Developer documentation for detailed information on camera driver development for Jetson platforms.
   • Join the Nvidia Developer forums for community support and additional insights.

7. Prototype and test incrementally

   • Start with a basic implementation and gradually add features to ensure compatibility with the Jetson platform.
   • Test thoroughly with various image sizes and framerates to verify the dynamic configuration capabilities.

By following these steps and guidelines, developers can create a custom camera sensor driver for the MIPI CSI transceiver on the Nvidia Jetson platform with the desired flexibility in frame parameter configuration. Remember to thoroughly test the implementation to ensure compatibility with the Jetson ecosystem and optimal performance.