For DDC/CI monitors, you would replace the WRITE_PORT_UCHAR call with a function that builds an I2C packet:
But for the embedded engineer building a custom display, or the developer reviving an old laptop with a broken EC interface, writing a minimal WDF driver that sends I2C or ACPI commands is a rewarding – albeit challenging – project. Just be prepared to disable driver signature enforcement or buy that EV certificate. brightness driver for windows 11
// BrightnessDriver.c #include <ntddk.h> #include <wdf.h> #define IOCTL_SET_BRIGHTNESS CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_BUFFERED, FILE_ANY_ACCESS) For DDC/CI monitors, you would replace the WRITE_PORT_UCHAR