Ported the Realtek rtl8192cu Wi-Fi driver to an NXP i.MX6 board.

Realtek's rtl8192cu Wi-Fi module is widely used for USB-based wireless connectivity, but porting it to ARM-based platforms such as the i.MX6 can be challenging due to missing open-source HAL support.

We were tasked with integrating this Wi-Fi module at the kernel level, ensuring stable operation and compatibility with the Yocto/Linux kernel on the i.MX6 platform.

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Problem Statement

• The Realtek rtl8192cu driver is missing a portable, board-agnostic HAL.
• Standard Linux distributions often blacklist this driver in favor of alternate community drivers (rtl8xxxu) with partial support.
• The i.MX6 platform required low-level changes for USB enumeration, interrupt handling, and network stack registration.
• Realtek's closed-source HAL posed major integration issues on custom embedded platforms.

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Solution

1. Kernel-Level Modifications:
   • Enabled and customized the native rtl8192cu driver in the Linux kernel for i.MX6.
   • Made necessary USB host controller adjustments for proper initialization and communication.
2. Driver Porting & HAL Bypass:
   • Identified missing HAL dependencies and created custom interface stubs to replace them.
   • Aligned driver’s initialization routines with i.MX6 memory and interrupt mapping.
3. Board-Specific Configuration:
   • Tailored device tree overlays and kernel configs for seamless integration.
   • Conducted low-level debugging with dmesg, modprobe, and trace logs to validate functionality.
4. Testing & Validation:
   • Validated Wi-Fi connectivity, DHCP lease, ping tests, and AP/STA modes.
   • Monitored performance metrics and ensured module stability during long uptime sessions.

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