Worked on the tianocore/edk2 repository to enhance the stability and standards compliance of serial I/O on ARM platforms by addressing a bug in the PL011UartLib SetControl() function. Focused on embedded systems and firmware development using C, the work involved implementing strict argument validation to ensure only supported control bits are accepted, aligning with UEFI specifications. This correction enabled SCT conformance tests to pass and restored proper UART control behavior, directly improving hardware compatibility for devices such as the Raspberry Pi 4. The approach emphasized reliability and traceability, linking changes to relevant issues and maintaining a clear sign-off chain.