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 {	(anonymous)
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.