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diff --git a/Documentation/userspace-api/media/dvb/fe-set-voltage.rst b/Documentation/userspace-api/media/dvb/fe-set-voltage.rst new file mode 100644 index 000000000..c66771830 --- /dev/null +++ b/Documentation/userspace-api/media/dvb/fe-set-voltage.rst @@ -0,0 +1,60 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: DTV.fe + +.. _FE_SET_VOLTAGE: + +******************** +ioctl FE_SET_VOLTAGE +******************** + +Name +==== + +FE_SET_VOLTAGE - Allow setting the DC level sent to the antenna subsystem. + +Synopsis +======== + +.. c:macro:: FE_SET_VOLTAGE + +``int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``voltage`` + an integer enumered value described at :c:type:`fe_sec_voltage` + +Description +=========== + +This ioctl allows to set the DC voltage level sent through the antenna +cable to 13V, 18V or off. + +Usually, a satellite antenna subsystems require that the digital TV +device to send a DC voltage to feed power to the LNBf. Depending on the +LNBf type, the polarization or the intermediate frequency (IF) of the +LNBf can controlled by the voltage level. Other devices (for example, +the ones that implement DISEqC and multipoint LNBf's don't need to +control the voltage level, provided that either 13V or 18V is sent to +power up the LNBf. + +.. attention:: if more than one device is connected to the same antenna, + setting a voltage level may interfere on other devices, as they may lose + the capability of setting polarization or IF. So, on those cases, setting + the voltage to SEC_VOLTAGE_OFF while the device is not is used is + recommended. + +Return Value +============ + +On success 0 is returned. + +On error -1 is returned, and the ``errno`` variable is set +appropriately. + +Generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. |