Calvin contributed to the geerlingguy/linux and torvalds/linux repositories by focusing on kernel maintenance and reliability, particularly within the Bluetooth and storage subsystems. He refactored Bluetooth HCI UART handling in C, removing duplicate functions and standardizing driver implementations to improve maintainability. Calvin also restored LZO compression level compatibility for Btrfs mounts, addressing user-facing issues and ensuring smoother file system operations. His work included stabilizing Bluetooth subsystem builds by adjusting Kconfig dependencies and reorganizing function definitions, which reduced compilation errors. Through targeted bug fixes and codebase refactoring, Calvin demonstrated depth in kernel development, Bluetooth protocol implementation, and file system management.