struct media_device — Media device
struct media_device {
struct device * dev;
struct media_devnode * devnode;
char model[32];
char driver_name[32];
char serial[40];
char bus_info[32];
u32 hw_revision;
u32 driver_version;
u64 topology_version;
u32 id;
struct ida entity_internal_idx;
int entity_internal_idx_max;
struct list_head entities;
struct list_head interfaces;
struct list_head pads;
struct list_head links;
struct list_head entity_notify;
struct mutex graph_mutex;
struct media_entity_graph pm_count_walk;
void * source_priv;
int (* enable_source) (struct media_entity *entity,struct media_pipeline *pipe);
void (* disable_source) (struct media_entity *entity);
int (* link_notify) (struct media_link *link, u32 flags,unsigned int notification);
}; Parent device
Media device node
Device model name
Optional device driver name. If not set, calls to
MEDIA_IOC_DEVICE_INFO will return dev->driver->name.
This is needed for USB drivers for example, as otherwise
they'll all appear as if the driver name was “usb”.
Device serial number (optional)
Unique and stable device location identifier
Hardware device revision
Device driver version
Monotonic counter for storing the version of the graph topology. Should be incremented each time the topology changes.
Unique ID used on the last registered graph object
Unique internal entity ID used by the graph traversal algorithms
Allocated internal entity indices
List of registered entities
List of registered interfaces
List of registered pads
List of registered links
List of registered entity_notify callbacks
Protects access to struct media_device data
Graph walk for power state walk. Access serialised using graph_mutex.
Driver Private data for enable/disable source handlers
Enable Source Handler function pointer
Disable Source Handler function pointer
Link state change notification callback. This callback is called with the graph_mutex held.
This structure represents an abstract high-level media device. It allows easy access to entities and provides basic media device-level support. The structure can be allocated directly or embedded in a larger structure.
The parent dev is a physical device. It must be set before registering the
media device.
model is a descriptive model name exported through sysfs. It doesn't have to
be unique.
enable_source is a handler to find source entity for the
sink entity and activate the link between them if source
entity is free. Drivers should call this handler before
accessing the source.
disable_source is a handler to find source entity for the
sink entity and deactivate the link between them. Drivers
should call this handler to release the source.
Bridge driver is expected to implement and set the handler when media_device is registered or when bridge driver finds the media_device during probe. Bridge driver sets source_priv with information necessary to run enable/disable source handlers.
Use-case: find tuner entity connected to the decoder entity and check if it is available, and activate the the link between them from enable_source and deactivate from disable_source.