BOOLEAN
VgaStartIO(
      PVOID HwDeviceExtension,
      PVIDEO_REQUEST_PACKET RequestPacket
  );

Routine Description:

    This routine is the main execution routine for the miniport driver. It
    acceptss a Video Request Packet, performs the request, and then returns
    with the appropriate status.

Arguments:

    HwDeviceExtension - Pointer to the miniport driver's adapter information.

    RequestPacket - Pointer to the video request packet. This structure
        contains all the parameters passed to the VideoIoControl function.

Return Value:

    This routine will return error codes from the various support routines
    and will also return ERROR_INSUFFICIENT_BUFFER for incorrectly sized
    buffers and ERROR_INVALID_FUNCTION for unsupported functions.