5.6. ioctl MEDIA_IOC_ENUM_ENTITIES

5.6.1. Name

MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties

5.6.2. Synopsis

MEDIA_IOC_ENUM_ENTITIES

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.