LIRC_SET_SEND_DUTY_CYCLE - Set the duty cycle of the carrier signal for IR transmit.
Get/set the duty cycle of the carrier signal for IR transmit.
Currently, no special meaning is defined for 0 or 100, but this could be used to switch off carrier generation in the future, so these values should be reserved.
On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.