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struct  MMAL_PORT_T
 

Typedefs

typedef struct MMAL_PORT_T MMAL_PORT_T
 
typedef void(* MMAL_PORT_BH_CB_T) (MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 

Enumerations

enum  MMAL_PORT_TYPE_T {
  MMAL_PORT_TYPE_UNKNOWN = 0, MMAL_PORT_TYPE_CONTROL, MMAL_PORT_TYPE_INPUT, MMAL_PORT_TYPE_OUTPUT,
  MMAL_PORT_TYPE_CLOCK, MMAL_PORT_TYPE_INVALID = 0xffffffff
}
 

Functions

MMAL_STATUS_T mmal_port_format_commit (MMAL_PORT_T *port)
 
MMAL_STATUS_T mmal_port_enable (MMAL_PORT_T *port, MMAL_PORT_BH_CB_T cb)
 
MMAL_STATUS_T mmal_port_disable (MMAL_PORT_T *port)
 
MMAL_STATUS_T mmal_port_flush (MMAL_PORT_T *port)
 
MMAL_STATUS_T mmal_port_parameter_set (MMAL_PORT_T *port, const MMAL_PARAMETER_HEADER_T *param)
 
MMAL_STATUS_T mmal_port_parameter_get (MMAL_PORT_T *port, MMAL_PARAMETER_HEADER_T *param)
 
MMAL_STATUS_T mmal_port_send_buffer (MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 
MMAL_STATUS_T mmal_port_connect (MMAL_PORT_T *port, MMAL_PORT_T *other_port)
 
MMAL_STATUS_T mmal_port_disconnect (MMAL_PORT_T *port)
 
uint8_t * mmal_port_payload_alloc (MMAL_PORT_T *port, uint32_t payload_size)
 
void mmal_port_payload_free (MMAL_PORT_T *port, uint8_t *payload)
 
MMAL_STATUS_T mmal_port_event_get (MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T **buffer, uint32_t event)
 

Port capabilities

The following flags describe the capabilities advertised by a port

#define MMAL_PORT_CAPABILITY_PASSTHROUGH   0x01
 
#define MMAL_PORT_CAPABILITY_ALLOCATION   0x02
 
#define MMAL_PORT_CAPABILITY_SUPPORTS_EVENT_FORMAT_CHANGE   0x04
 

Detailed Description

Definition of a MMAL port and its associated API

Macro Definition Documentation

◆ MMAL_PORT_CAPABILITY_ALLOCATION

#define MMAL_PORT_CAPABILITY_ALLOCATION   0x02

The port wants to allocate the buffer payloads. This signals a preference that payload allocation should be done on this port for efficiency reasons.

Definition at line 64 of file mmal_port.h.

◆ MMAL_PORT_CAPABILITY_PASSTHROUGH

#define MMAL_PORT_CAPABILITY_PASSTHROUGH   0x01

The port is pass-through and doesn't need buffer headers allocated

Definition at line 61 of file mmal_port.h.

◆ MMAL_PORT_CAPABILITY_SUPPORTS_EVENT_FORMAT_CHANGE

#define MMAL_PORT_CAPABILITY_SUPPORTS_EVENT_FORMAT_CHANGE   0x04

The port supports format change events. This applies to input ports and is used to let the client know whether the port supports being reconfigured via a format change event (i.e. without having to disable the port).

Definition at line 68 of file mmal_port.h.

Typedef Documentation

◆ MMAL_PORT_BH_CB_T

typedef void(* MMAL_PORT_BH_CB_T) (MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)

Definition of the callback used by a port to send a MMAL_BUFFER_HEADER_T back to the user.

Parameters
portThe port sending the buffer header.
bufferThe buffer header being sent.

Definition at line 132 of file mmal_port.h.

◆ MMAL_PORT_T

typedef struct MMAL_PORT_T MMAL_PORT_T

Definition of a port. A port is the entity that is exposed by components to receive or transmit buffer headers (MMAL_BUFFER_HEADER_T). A port is defined by its MMAL_ES_FORMAT_T.

It may be possible to override the buffer requirements of a port by using the MMAL_PARAMETER_BUFFER_REQUIREMENTS parameter.

Enumeration Type Documentation

◆ MMAL_PORT_TYPE_T

List of port types

Enumerator
MMAL_PORT_TYPE_UNKNOWN 

Unknown port type

MMAL_PORT_TYPE_CONTROL 

Control port

MMAL_PORT_TYPE_INPUT 

Input port

MMAL_PORT_TYPE_OUTPUT 

Output port

MMAL_PORT_TYPE_CLOCK 

Clock port

MMAL_PORT_TYPE_INVALID 

Dummy value to force 32bit enum

Definition at line 45 of file mmal_port.h.

Function Documentation

◆ mmal_port_connect()

MMAL_STATUS_T mmal_port_connect ( MMAL_PORT_T port,
MMAL_PORT_T other_port 
)

Connect an output port to an input port.

When connected and enabled, buffers will automatically progress from the output port to the input port when they become available, and released back to the output port when no longer required by the input port.

Ports can be given either way around, but one must be an output port and the other must be an input port. Neither can be connected or enabled already. The format of the output port will be applied to the input port on connection.

Parameters
portOne of the ports to connect.
other_portThe other port to connect.
Returns
MMAL_SUCCESS on success.

◆ mmal_port_disable()

MMAL_STATUS_T mmal_port_disable ( MMAL_PORT_T port)

Disable processing on a port

Disabling a port will stop all processing on this port and return all (non-processed) buffer headers to the client.

If this is a connected output port, the input port to which it is connected shall also be disabled. Any buffer pool shall be released.

Parameters
portport to disable
Returns
MMAL_SUCCESS on success

◆ mmal_port_disconnect()

MMAL_STATUS_T mmal_port_disconnect ( MMAL_PORT_T port)

Disconnect a connected port.

If the port is not connected, an error will be returned. Otherwise, if the ports are enabled, they will be disabled and any buffer pool created will be freed.

Parameters
portThe ports to disconnect.
Returns
MMAL_SUCCESS on success.

◆ mmal_port_enable()

MMAL_STATUS_T mmal_port_enable ( MMAL_PORT_T port,
MMAL_PORT_BH_CB_T  cb 
)

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.
Parameters
portport to enable
cbcallback use by the port to send a MMAL_BUFFER_HEADER_T back
Returns
MMAL_SUCCESS on success

◆ mmal_port_event_get()

MMAL_STATUS_T mmal_port_event_get ( MMAL_PORT_T port,
MMAL_BUFFER_HEADER_T **  buffer,
uint32_t  event 
)

Get an empty event buffer header from a port

Parameters
portThe port from which to get the event buffer header.
bufferThe address of a buffer header pointer, which will be set on return.
eventThe specific event FourCC required. See the pre-defined events.
Returns
MMAL_SUCCESS on success

◆ mmal_port_flush()

MMAL_STATUS_T mmal_port_flush ( MMAL_PORT_T port)

Ask a port to release all the buffer headers it currently has.

Flushing a port will ask the port to send all the buffer headers it currently has to the client. Flushing is an asynchronous request and the flush call will return before all the buffer headers are returned to the client. It is up to the client to keep a count on the buffer headers to know when the flush operation has completed. It is also important to note that flushing will also reset the state of the port and any processing which was buffered by the port will be lost.

Attention
Flushing a connected port behaviour TBD.
Parameters
portThe port to flush.
Returns
MMAL_SUCCESS on success

◆ mmal_port_format_commit()

MMAL_STATUS_T mmal_port_format_commit ( MMAL_PORT_T port)

Commit format changes on a port.

Parameters
portThe port for which format changes are to be committed.
Returns
MMAL_SUCCESS on success

◆ mmal_port_parameter_get()

MMAL_STATUS_T mmal_port_parameter_get ( MMAL_PORT_T port,
MMAL_PARAMETER_HEADER_T param 
)

Get a parameter from a port. The size field must be set on input to the maximum size of the parameter (including the header) and will be set on output to the actual size of the parameter retrieved.

Note
If MMAL_ENOSPC is returned, the parameter is larger than the size given. The given parameter will have been filled up to its size and then the size field set to the full parameter's size. This can be used to resize the parameter buffer so that a second call should succeed.
Parameters
portThe port to which the request is sent.
paramThe pointer to the header of the parameter to get.
Returns
MMAL_SUCCESS on success

◆ mmal_port_parameter_set()

MMAL_STATUS_T mmal_port_parameter_set ( MMAL_PORT_T port,
const MMAL_PARAMETER_HEADER_T param 
)

Set a parameter on a port.

Parameters
portThe port to which the request is sent.
paramThe pointer to the header of the parameter to set.
Returns
MMAL_SUCCESS on success

◆ mmal_port_payload_alloc()

uint8_t* mmal_port_payload_alloc ( MMAL_PORT_T port,
uint32_t  payload_size 
)

Allocate a payload buffer. This allows a client to allocate memory for a payload buffer based on the preferences of a port. This for instance will allow the port to allocate memory which can be shared between the host processor and videocore.

See mmal_pool_create_with_allocator().

Parameters
portPort responsible for allocating the memory.
payload_sizeSize of the payload buffer which will be allocated.
Returns
Pointer to the allocated memory.

◆ mmal_port_payload_free()

void mmal_port_payload_free ( MMAL_PORT_T port,
uint8_t *  payload 
)

Free a payload buffer. This allows a client to free memory allocated by a previous call to mmal_port_payload_alloc.

See mmal_pool_create_with_allocator().

Parameters
portPort responsible for allocating the memory.
payloadPointer to the memory to free.

◆ mmal_port_send_buffer()

MMAL_STATUS_T mmal_port_send_buffer ( MMAL_PORT_T port,
MMAL_BUFFER_HEADER_T buffer 
)

Send a buffer header to a port.

Parameters
portThe port to which the buffer header is to be sent.
bufferThe buffer header to send.
Returns
MMAL_SUCCESS on success