Hsin-Hsiung Wang focused on enhancing the reliability of SMC handling for the Mediatek platform within the zephyrproject-rtos/trusted-firmware-a repository. He addressed a critical correctness issue by refactoring the smc_handler_t function pointer’s return type from uintptr_t to u_register_t, aligning it with platform calling conventions and improving type safety. This change reduced ABI-related risks in secure monitor interactions and ensured consistency across SMC services. Working primarily in C, Hsin-Hsiung applied his expertise in embedded systems, firmware development, and system programming to deliver a targeted, in-depth fix that improved maintainability and correctness in a complex, security-sensitive codebase.