ioctl MEDIA_IOC_ENUM_LINKS

&manvol;

MEDIA_IOC_ENUM_LINKS

Enumerate all pads and links for a given entity

    	int ioctl
    	int fd
    	int request
    	struct media_links_enum *argp

## Arguments

`fd`

- File descriptor returned by `open()`.

`request`

- MEDIA_IOC_ENUM_LINKS

`argp`

## Description

To enumerate pads and/or links for a given entity, applications set the entity field of a &media-links-enum; structure and initialize the &media-pad-desc; and &media-link-desc; structure arrays pointed by the pads and links fields. They then call the MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this structure.

If the pads field is not NULL, the driver fills the pads array with information about the entity's pads. The array must have enough room to store all the entity's pads. The number of pads can be retrieved with the &MEDIA-IOC-ENUM-ENTITIES; ioctl.

If the links field is not NULL, the driver fills the links array with information about the entity's outbound links. The array must have enough room to store all the entity's outbound links. The number of outbound links can be retrieved with the &MEDIA-IOC-ENUM-ENTITIES; ioctl.

Only forward links that originate at one of the entity's source pads are returned during the enumeration process.

## struct media_links_enum

&cs-str;
__u32 | entity | Entity id, set by the application.
&media-pad-desc; | *pads | Pointer to a pads array allocated by the application. Ignored if NULL.
&media-link-desc; | *links | Pointer to a links array allocated by the application. Ignored if NULL.

## struct media_pad_desc

&cs-str;
__u32 | entity | ID of the entity this pad belongs to.
__u16 | index | 0-based pad index.
__u32 | flags | Pad flags, see media-pad-flag for more details.

## struct media_link_desc

&cs-str;
&media-pad-desc; | source | Pad at the origin of this link.
&media-pad-desc; | sink | Pad at the target of this link.
__u32 | flags | Link flags, see media-link-flag for more details.

&return-value;

EINVAL

- The &media-links-enum; id references a non-existing entity.