| .. -*- coding: utf-8; mode: rst -*- |
| |
| .. _media_ioc_enum_links: |
| |
| ************************** |
| ioctl MEDIA_IOC_ENUM_LINKS |
| ************************** |
| |
| Name |
| ==== |
| |
| MEDIA_IOC_ENUM_LINKS - Enumerate all pads and links for a given entity |
| |
| |
| Synopsis |
| ======== |
| |
| .. cpp:function:: int ioctl( int fd, int request, struct media_links_enum *argp ) |
| |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :ref:`open() <media-func-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 struct :ref:`media_links_enum <media-links-enum>` |
| structure and initialize the struct |
| :ref:`media_pad_desc <media-pad-desc>` and struct |
| :ref:`media_link_desc <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 :ref:`MEDIA_IOC_ENUM_ENTITIES`. |
| |
| 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 :ref:`MEDIA_IOC_ENUM_ENTITIES`. |
| |
| Only forward links that originate at one of the entity's source pads are |
| returned during the enumeration process. |
| |
| |
| .. _media-links-enum: |
| |
| .. flat-table:: struct media_links_enum |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| |
| - .. row 1 |
| |
| - __u32 |
| |
| - ``entity`` |
| |
| - Entity id, set by the application. |
| |
| - .. row 2 |
| |
| - struct :ref:`media_pad_desc <media-pad-desc>` |
| |
| - \*\ ``pads`` |
| |
| - Pointer to a pads array allocated by the application. Ignored if |
| NULL. |
| |
| - .. row 3 |
| |
| - struct :ref:`media_link_desc <media-link-desc>` |
| |
| - \*\ ``links`` |
| |
| - Pointer to a links array allocated by the application. Ignored if |
| NULL. |
| |
| |
| |
| .. _media-pad-desc: |
| |
| .. flat-table:: struct media_pad_desc |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| |
| - .. row 1 |
| |
| - __u32 |
| |
| - ``entity`` |
| |
| - ID of the entity this pad belongs to. |
| |
| - .. row 2 |
| |
| - __u16 |
| |
| - ``index`` |
| |
| - 0-based pad index. |
| |
| - .. row 3 |
| |
| - __u32 |
| |
| - ``flags`` |
| |
| - Pad flags, see :ref:`media-pad-flag` for more details. |
| |
| |
| |
| .. _media-link-desc: |
| |
| .. flat-table:: struct media_link_desc |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| |
| - .. row 1 |
| |
| - struct :ref:`media_pad_desc <media-pad-desc>` |
| |
| - ``source`` |
| |
| - Pad at the origin of this link. |
| |
| - .. row 2 |
| |
| - struct :ref:`media_pad_desc <media-pad-desc>` |
| |
| - ``sink`` |
| |
| - Pad at the target of this link. |
| |
| - .. row 3 |
| |
| - __u32 |
| |
| - ``flags`` |
| |
| - Link flags, see :ref:`media-link-flag` for more details. |
| |
| |
| 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 |
| :ref:`Generic Error Codes <gen-errors>` chapter. |
| |
| EINVAL |
| The struct :ref:`media_links_enum <media-links-enum>` ``id`` |
| references a non-existing entity. |