Function mmal_sys::mmal_port_enable

pub unsafe extern "C" fn mmal_port_enable(
    port: *mut MMAL_PORT_T, 
    cb: MMAL_PORT_BH_CB_T
) -> Type

Enable processing on a port

If this port is connected to another, the given callback must be NULL, while for a disconnected port, the callback must be non-NULL.

If this is a connected output port and is successfully enabled:

• The port shall be populated with a pool of buffers, allocated as required, according to the buffer_num and buffer_size values.
• The input port to which it is connected shall be set to the same buffer configuration and then be enabled. Should that fail, the original port shall be disabled.

@param port port to enable @param cb callback use by the port to send a \ref MMAL_BUFFER_HEADER_T back @return MMAL_SUCCESS on success