MEDIA_IOC_ENUM_LINKS — Enumerate all pads and links for a given entity
int ioctl( | int fd, |
| int request, | |
struct media_links_enum *argp); |
To enumerate pads and/or links for a given entity, applications set
the entity field of a struct media_links_enum structure and initialize the
struct media_pad_desc and struct 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.
Table L.9. struct media_links_enum
| __u32 | entity | Entity id, set by the application. |
| struct media_pad_desc | *pads | Pointer to a pads array allocated by the application. Ignored if NULL. |
| struct media_link_desc | *links | Pointer to a links array allocated by the application. Ignored if NULL. |
Table L.10. struct media_pad_desc
| __u32 | entity | ID of the entity this pad belongs to. |
| __u16 | index | 0-based pad index. |
| __u32 | flags | Pad flags, see Table 16.4, “Media pad flags” for more details. |
Table L.11. struct media_link_desc
| struct media_pad_desc | source | Pad at the origin of this link. |
| struct media_pad_desc | sink | Pad at the target of this link. |
| __u32 | flags | Link flags, see Table 16.5, “Media link flags” for more details. |
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.
The struct media_links_enum id references
a non-existing entity.