Compiling and Modifying the option.ko Driver on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users are experiencing difficulties when attempting to modify and compile the option.ko driver for USB serial devices on the Nvidia Jetson Orin Nano Dev Board. Symptoms include compilation failures, inability to detect connected devices, and system crashes after connecting USB modules. The issue occurs primarily during the driver modification process, particularly when users try to integrate specific driver code (e.g., for SIMCOM devices) into the existing option.c file. The problem seems to be consistent, impacting users who are not familiar with kernel modifications or who lack experience in cross-compilation.

Context

• Hardware: Nvidia Jetson Orin Nano Dev Board.
• Software: Users are typically using Ubuntu-based systems aligned with the Nvidia L4T (Linux for Tegra) releases.
• Frequency: This issue appears to be a common hurdle for developers working with custom drivers on this platform.
• Impact: Users report that these difficulties hinder their ability to utilize USB devices effectively, affecting overall functionality and user experience.

Possible Causes

1. Incorrect Kernel Source: Users may not be using the correct version of the kernel source that matches their running kernel.

   • Mismatched configurations can lead to compilation errors or runtime issues.

2. Configuration Errors: Failure to set up the kernel configuration correctly before compiling.

   • Missing or incorrect CONFIG_LOCALVERSION settings can prevent modules from loading properly.

3. Driver Issues: Existing drivers may not support the specific USB device being connected.

   • This can lead to detection failures or system instability.

4. Environmental Factors: Power supply issues or overheating could affect performance.

   • Users have noted temperature increases and fan failures during operation.

5. User Errors: Lack of familiarity with kernel compilation processes can lead to mistakes in command execution or directory navigation.

Troubleshooting Steps, Solutions & Fixes

Step-by-Step Instructions

1. Verify Kernel Version:

   • Run uname -r to check your current kernel version.
   • Ensure you are downloading the corresponding kernel source from Nvidia’s official site.

2. Download Correct Source Code:

   • Use the command:

     sudo apt-get install linux-source
     

   • Alternatively, download from Nvidia’s Jetson Linux Archive.

3. Extract Kernel Source:

   • After downloading, extract the source:

     tar -xjf public_sources.tbz2
     cd Linux_for_Tegra/source/public
     tar -xjf kernel_src.tbz2
     

4. Set Environment Variables:

   • Set $TOP and output directory:

     export TOP=`pwd`
     export TEGRA_KERNEL_OUT=~/kernel_out
     

5. Prepare Kernel Configuration:

   • Clean previous builds:

     sudo make mrproper
     

   • Configure kernel options:

     make O=$TEGRA_KERNEL_OUT tegra_defconfig
     

6. Edit option.c:

   • Navigate to drivers/usb/serial/ and edit option.c as per requirements.

7. Compile Modules:

   • Prepare for module compilation:

     make O=$TEGRA_KERNEL_OUT modules_prepare
     

   • Compile the modified module:

     make O=$TEGRA_KERNEL_OUT -C /lib/modules/`uname -r`/build M=`pwd`/drivers/usb/serial obj-m=option.o modules
     

8. Install New Module:

   • Replace existing option.ko with your compiled version in /lib/modules/$(uname -r)/kernel/drivers/usb/serial/.

9. Run Dependency Module Command:

   • Execute depmod to refresh module dependencies.

10. Testing:

    • Use lsmod to check if your module is loaded.
    • Connect your USB device and monitor /dev for new entries like /dev/ttyUSB0.

Recommended Fixes & Workarounds

• If issues persist, consider building the entire kernel image with a new CONFIG_LOCALVERSION.
• Use a protocol analyzer to diagnose USB communication issues if crashes occur.
• For persistent detection problems, check udev rules that may affect device naming or permissions.

Best Practices for Future Prevention

• Always ensure that your kernel source matches your running kernel version.
• Maintain backups of working configurations before making changes.
• Familiarize yourself with basic kernel compilation commands and structure before attempting modifications.

Code Snippets & Commands

# Check current kernel version
uname -r

# Clean previous builds before starting a new one
sudo make mrproper

# Compile modified driver module
make O=$TEGRA_KERNEL_OUT modules_prepare
make O=$TEGRA_KERNEL_OUT -C /lib/modules/`uname -r`/build M=`pwd`/drivers/usb/serial obj-m=option.o modules

# Refresh module dependencies after installation
depmod

# Check loaded modules after connecting the USB device
lsmod | grep option 

Unresolved Aspects & Further Investigation Needed

• Some users reported issues with specific configurations not being recognized after modifications; further investigation into Nvidia’s documentation might be necessary.
• Monitoring logs during runtime could provide additional insights into recurring crashes or detection failures.

This structured approach should assist users in troubleshooting and resolving issues related to modifying and compiling the option.ko driver on their Nvidia Jetson Orin Nano Dev Board effectively.