@brief Get the event file descriptor.
@param line GPIO line object.
@return Number of the event file descriptor or -1 if the user tries to
retrieve the descriptor from a line that wasn't configured for
event monitoring.
Users may want to poll the event file descriptor on their own. This routine
allows to access it.
@brief Get the event file descriptor. @param line GPIO line object. @return Number of the event file descriptor or -1 if the user tries to retrieve the descriptor from a line that wasn't configured for event monitoring.
Users may want to poll the event file descriptor on their own. This routine allows to access it.