5.6. ioctl MEDIA_IOC_ENUM_ENTITIES

5.6.1. Name

MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties

5.6.2. Synopsis

int ioctl(int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp)

5.6.3. Arguments

fd
File descriptor returned by open().
argp
Pointer to struct media_entity_desc.

5.6.4. Description

To query the attributes of an entity, applications set the id field of a struct media_entity_desc structure and call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this structure. The driver fills the rest of the structure or returns an EINVAL error code when the id is invalid.

Entities can be enumerated by or'ing the id with the MEDIA_ENT_ID_FLAG_NEXT flag. The driver will return information about the entity with the smallest id strictly larger than the requested one ('next entity'), or the EINVAL error code if there is none.

Entity IDs can be non-contiguous. Applications must not try to enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing id's until they get an error.

media_entity_desc
struct media_entity_desc
__u32 id     Entity ID, set by the application. When the ID is or'ed with MEDIA_ENT_ID_FLAG_NEXT, the driver clears the flag and returns the first entity with a larger ID. Do not expect that the ID will always be the same for each instance of the device. In other words, do not hardcode entity IDs in an application.
char name[32]     Entity name as an UTF-8 NULL-terminated string. This name must be unique within the media topology.
__u32 type     Entity type, see Media entity functions for details.
__u32 revision     Entity revision. Always zero (obsolete)
__u32 flags     Entity flags, see Media entity flags for details.
__u32 group_id     Entity group ID. Always zero (obsolete)
__u16 pads     Number of pads
__u16 links     Total number of outbound links. Inbound links are not counted in this field.
__u32 reserved[4]     Reserved for future extensions. Drivers and applications must set the array to zero.
union
  struct dev   Valid for (sub-)devices that create a single device node.
    __u32 major Device node major number.
    __u32 minor Device node minor number.
  __u8 raw[184]    

5.6.5. Return Value

On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.

EINVAL
The struct media_entity_desc id references a non-existing entity.