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path: root/drivers/media/media-entity.c
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2016-01-11[media] media: don't try to empty links list in media_entity_cleanup()Javier Martinez Canillas
The media_entity_cleanup() function only cleans up the entity links list but this operation is already made in media_device_unregister_entity(). In most cases this should be harmless (besides having duplicated code) since the links list would be empty so the iteration would not happen but the links list is initialized in media_device_register_entity() so if a driver fails to register an entity with a media device and clean up the entity in the error path, a NULL deference pointer error will happen. So don't try to empty the links list in media_entity_cleanup() since is either done already or haven't been initialized yet. Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
2016-01-11[media] media-entity: protect object creation/removal using spin lockMauro Carvalho Chehab
Some parts of the media controller are using mutexes while others are using spin locks in order to protect creation and removal of elements in the graph. That's wrong! Also, the V4L2 core can remove graph elements on non-interactive context: BUG: sleeping function called from invalid context at include/linux/sched.h:2776 Fix it by always using spin locks for graph element addition/removal, just like entity creation/removal is protected at media-device.c Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media-device: remove interfaces and interface linksMauro Carvalho Chehab
Just like what's done with entities, when the media controller is unregistered, release any interface and interface links that might still be there. Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media-entity: unregister entity linksMauro Carvalho Chehab
Add functions to explicitly unregister all entity links. This function is called automatically when an entity link is destroyed. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media_device: add a topology version fieldMauro Carvalho Chehab
Every time a graph object is added or removed, the version of the topology changes. That's a requirement for the new MEDIA_IOC_G_TOPOLOGY, in order to allow userspace to know that the topology has changed after a previous call to it. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media-device: add pads and links to media_deviceMauro Carvalho Chehab
The MC next gen API sends objects to userspace grouped by their types. In the case of pads and links, in order to improve performance and have a simpler code, the best is to store them also on separate linked lists at MC. If we don't do that, we would need this kind of interaction to send data to userspace (code is in structured english): for each entity: for each pad: store pads for each entity: for each link: store link for each interface: for each link: store link With would require one nested loop for pads and two nested loops for links. By using separate linked lists for them, just one loop would be enough. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: move mdev list init to gobjMauro Carvalho Chehab
Let's control the topology changes inside the graph_object. So, move the addition and removal of interfaces/entities from the mdev lists to media_gobj_init() and media_gobj_remove(). The main reason is that mdev should have lists for all object types, as the new MC api will require to store objects in separate places. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: report if a pad is sink or source at debug msgMauro Carvalho Chehab
Sometimes, it is important to see if the created pad is sink or source. Add info to track that. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: add a linked list to track interfaces by mdevMauro Carvalho Chehab
The media device should list the interface objects, so add a linked list for those interfaces in struct media_device. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media-entity: add a helper function to create interfaceMauro Carvalho Chehab
As we'll be adding other interface types in the future, put the common interface create code on a separate function. Suggested-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: add support to link interfaces and entitiesMauro Carvalho Chehab
Now that we have a new graph object called "interfaces", we need to be able to link them to the entities. Add a linked list to the interfaces to allow them to be linked to the entities. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: make link debug printk more genericMauro Carvalho Chehab
Remove entity name from the link as this exists only if the object type is PAD on both link ends. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: make add link more genericMauro Carvalho Chehab
The media_entity_add_link() function takes an entity as an argument just to get the list head. Make it more generic by changing the function argument to list_head. No functional changes. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: convert links from array to listMauro Carvalho Chehab
The entire logic that represent graph links were developed on a time where there were no needs to dynamic remove links. So, although links are created/removed one by one via some functions, they're stored as an array inside the entity struct. As the array may grow, there's a logic inside the code that checks if the amount of space is not enough to store the needed links. If it isn't the core uses krealloc() to change the size of the link, with is bad, as it leaves the memory fragmented. So, convert links into a list. Also, currently, both source and sink entities need the link at the graph traversal logic inside media_entity. So there's a logic duplicating all links. That makes it to spend twice the memory needed. This is not a big deal for today's usage, where the number of links are not big. Yet, if during the MC workshop discussions, it was said that IIO graphs could have up to 4,000 entities. So, we may want to remove the duplication on some future. The problem is that it would require a separate linked list to store the backlinks inside the entity, or to use a more complex algorithm to do graph backlink traversal, with is something that the current graph traversal inside the core can't cope with. So, let's postpone a such change if/when it is actually needed. It should also be noticed that the media_link structure uses 44 bytes on 32-bit architectures and 84 bytes on 64-bit architecture. It will thus be allocated out of the 64-bytes and 96-bytes pools respectively. That's a 12.5% memory waste on 64-bit architectures and 31.25% on 32-bit architecture. A linked list is less efficient than an array in this case, but this could later be optimized if we can get rid of the reverse links (with would reduce memory allocation by 50%). Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: Don't accept early-created linksMauro Carvalho Chehab
Links are graph objects that represent the links of two already existing objects in the graph. While with the current implementation, it is possible to create the links earlier, It doesn't make any sense to allow linking two objects when they are not both created. So, remove the code that would be handling those early-created links and add a BUG_ON() to ensure that. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: add functions to allow creating interfacesMauro Carvalho Chehab
Interfaces are different than entities: they represent a Kernel<->userspace interaction, while entities represent a piece of hardware/firmware/software that executes a function. Let's distinguish them by creating a separate structure to store the interfaces. Later patches should change the existing drivers and logic to split the current interface embedded inside the entity structure (device nodes) into a separate object of the graph. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: use entity.graph_obj.mdev instead of .parentJavier Martinez Canillas
The struct media_entity has a .parent field that stores a pointer to the parent struct media_device. But recently a media_gobj was embedded into the entities and since struct media_gojb already has a pointer to a struct media_device in the .mdev field, the .parent field becomes redundant and can be removed. This patch replaces all the usage of .parent by .graph_obj.mdev so that field will become unused and can be removed on a later patch. No functional changes. The transformation was made using the following coccinelle spatch: @@ struct media_entity *me; @@ - me->parent + me->graph_obj.mdev @@ struct media_entity *link; @@ - link->source->entity->parent + link->source->entity->graph_obj.mdev @@ struct exynos_video_entity *ve; @@ - ve->vdev.entity.parent + ve->vdev.entity.graph_obj.mdev Suggested-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: rename the function that create pad linksMauro Carvalho Chehab
With the new API, a link can be either between two PADs or between an interface and an entity. So, we need to use a better name for the function that create links between two pads. So, rename the such function to media_create_pad_link(). No functional changes. This patch was created via this shell script: for i in $(find drivers/media -name '*.[ch]' -type f) $(find drivers/staging/media -name '*.[ch]' -type f) $(find include/ -name '*.h' -type f) ; do sed s,media_entity_create_link,media_create_pad_link,g <$i >a && mv a $i; done Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Tested-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: add a debug message to warn about gobj creation/removalMauro Carvalho Chehab
It helps to check if the media controller is doing the right thing with the object creation and removal. No extra code/data will be produced if DEBUG or CONFIG_DYNAMIC_DEBUG is not enabled. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: use media_gobj inside linksMauro Carvalho Chehab
Just like entities and pads, links also need to have unique Object IDs along a given media controller. So, let's add a media_gobj inside it and initialize the object then a new link is created. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Tested-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: use media_gobj inside padsMauro Carvalho Chehab
PADs also need unique object IDs that won't conflict with the entity object IDs. The pad objects are currently created via media_entity_init() and, once created, never change. While this will likely change in the future in order to support dynamic changes, for now we'll keep PADs as arrays and initialize the media_gobj embedded structs when registering the entity. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Tested-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: use media_gobj inside entitiesMauro Carvalho Chehab
As entities are graph objects, let's embed media_gobj on it. That ensures an unique ID for entities that can be global along the entire media controller. For now, we'll keep the already existing entity ID. Such field need to be dropped at some point, but for now, let's not do this, to avoid needing to review all drivers and the userspace apps. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Tested-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: add a common struct to be embed on media graph objectsMauro Carvalho Chehab
Due to the MC API proposed changes, we'll need to have an unique object ID for all graph objects, and have some shared fields that will be common on all media graph objects. Right now, the only common object is the object ID, but other fields will be added later on. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: create a macro to get entity IDMauro Carvalho Chehab
Instead of accessing directly entity.id, let's create a macro, as this field will be moved into a common struct later on. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-01-11[media] media: get rid of unused "extra_links" param on media_entity_init()Mauro Carvalho Chehab
Currently, media_entity_init() creates an array with the links, allocated at init time. It provides a parameter (extra_links) that would allocate more links than the current needs, but this is not used by any driver. As we want to be able to do dynamic link allocation/removal, we'll need to change the implementation of the links. So, before doing that, let's first remove that extra unused parameter, in order to cleanup the interface first. Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2015-10-01[media] media-entity.c: get rid of var length arraysMauro Carvalho Chehab
Fix those sparse warnings: drivers/media/media-entity.c:238:17: warning: Variable length array is used. drivers/media/media-entity.c:239:17: warning: Variable length array is used. That allows sparse and other code check tools to verify if the function is using more stack than allowed. It also solves a bad Kernel pratice of using var length arrays at the stack. Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2015-08-16[media] media: Correctly notify about the failed pipeline validationSakari Ailus
On the place of the source entity name, the sink entity name was printed. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2014-11-03[media] media: Fix a compiler warning in media_entity_pipeline_start()Sakari Ailus
Patch "[media] media: Print information on failed link validation" cause a harmless compiler warning in printing a debug message. Fix this. The type casting is done do ensure the type really is suitable for printing as %u, as find_first_zero_bit() does return int on some architectures and unsigned long on others. Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2014-11-03[media] media: Print information on failed link validationSakari Ailus
The Media controller doesn't tell much to the user in cases such as pipeline startup failure. The link validation is the most common media graph (or in V4L2's case, format) related reason for the failure. In more complex pipelines the reason may not always be obvious to the user, so point them to look at the right direction. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2013-12-04[media] media: Check for active links on pads with MEDIA_PAD_FL_MUST_CONNECT ↵Sakari Ailus
flag Do not allow streaming if a pad with MEDIA_PAD_FL_MUST_CONNECT flag is not connected by an active link. This patch makes it possible to avoid drivers having to check for the most common case of link state validation: a sink pad that must be connected. Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2013-08-18[media] media: Add support for circular graph traversalLaurent Pinchart
The graph traversal API (media_entity_graph_walk_*) doesn't support cyclic graphs and will fail to correctly walk a graph when circular links exist. Support circular graph traversal by checking whether an entity has already been visited before pushing it to the stack. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Acked-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
2013-06-19[media] media: Add a function removing all links of a media entitySylwester Nawrocki
This function allows to remove all media entity's links to other entities, leaving no references to a media entity's links array at its remote entities. Currently, when a driver of some entity is removed it will free its media entities links[] array, leaving dangling pointers at other entities that are part of same media graph. This is troublesome when drivers of a media device entities are in separate kernel modules, removing only some modules will leave others in an incorrect state. This function is intended to be used when an entity is being unregistered from a media device. With an assumption that normally the media links should be created between media entities registered to a media device, with the graph mutex held. Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2013-06-12[media] media: Change media device link_notify behaviourSylwester Nawrocki
Currently the media device link_notify callback is invoked before the actual change of state of a link when the link is being enabled, and after the actual change of state when the link is being disabled. This doesn't allow a media device driver to perform any operations on a full graph before a link is disabled, as well as performing any tasks on a modified graph right after a link's state is changed. This patch modifies signature of the link_notify callback. This callback is now called always before and after a link's state change. To distinguish the notifications a 'notification' argument is added to the link_notify callback: MEDIA_DEV_NOTIFY_PRE_LINK_CH indicates notification before link's state change and MEDIA_DEV_NOTIFY_POST_LINK_CH corresponds to a notification after link flags change. [mchehab@redhat.com: whitespace cleanups] Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2013-06-08[media] media: Rename media_entity_remote_source to media_entity_remote_padAndrzej Hajda
Function media_entity_remote_source actually returns the remote pad to the given one, regardless if this is the source or the sink pad. Name media_entity_remote_pad is more adequate for this function. Signed-off-by: Andrzej Hajda <a.hajda@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14[media] media: Add link_validate() op to check links to the sink padSakari Ailus
The purpose of the link_validate() op is to allow an entity driver to ensure that the properties of the pads at the both ends of the link are suitable for starting the pipeline. link_validate is called on sink pads on active links which belong to the active part of the graph. Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-04-17[media] media: Properly handle link flags in link setup, link notify callbackLaurent Pinchart
The link flags were not properly handled in __media_entity_setup_link which could lead to link_notify callback to be called when the flags are not modified. Fix this. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-03-22[media] media: Pipelines and media streamsLaurent Pinchart
Drivers often need to associate pipeline objects to entities, and to take stream state into account when configuring entities and links. The pipeline API helps drivers manage that information. When starting streaming, drivers call media_entity_pipeline_start(). The function marks all entities connected to the given entity through enabled links, either directly or indirectly, as streaming. Similarly, when stopping the stream, drivers call media_entity_pipeline_stop(). The media_entity_pipeline_start() function takes a pointer to a media pipeline and stores it in every entity in the graph. Drivers should embed the media_pipeline structure in higher-level pipeline structures and can then access the pipeline through the media_entity structure. Link configuration will fail with -EBUSY by default if either end of the link is a streaming entity, unless the link is marked with the MEDIA_LNK_FL_DYNAMIC flag. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-03-22[media] media: Links setupLaurent Pinchart
Create the following ioctl and implement it at the media device level to setup links. - MEDIA_IOC_SETUP_LINK: Modify the properties of a given link The only property that can currently be modified is the ENABLED link flag to enable/disable a link. Links marked with the IMMUTABLE link flag can not be enabled or disabled. Enabling or disabling a link has effects on entities' use count. Those changes are automatically propagated through the graph. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-03-22[media] media: Entity use countLaurent Pinchart
Due to the wide differences between drivers regarding power management needs, the media controller does not implement power management. However, the media_entity structure includes a use_count field that media drivers can use to track the number of users of every entity for power management needs. The use_count field is owned by media drivers and must not be touched by entity drivers. Access to the field must be protected by the media device graph_mutex lock. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-03-22[media] media: Entity graph traversalSakari Ailus
Add media entity graph traversal. The traversal follows enabled links by depth first. Traversing graph backwards is prevented by comparing the next possible entity in the graph with the previous one. Multiply connected graphs are thus not supported. Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Vimarsh Zutshi <vimarsh.zutshi@gmail.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-03-22[media] media: Entities, pads and linksLaurent Pinchart
As video hardware pipelines become increasingly complex and configurable, the current hardware description through v4l2 subdevices reaches its limits. In addition to enumerating and configuring subdevices, video camera drivers need a way to discover and modify at runtime how those subdevices are connected. This is done through new elements called entities, pads and links. An entity is a basic media hardware building block. It can correspond to a large variety of logical blocks such as physical hardware devices (CMOS sensor for instance), logical hardware devices (a building block in a System-on-Chip image processing pipeline), DMA channels or physical connectors. A pad is a connection endpoint through which an entity can interact with other entities. Data (not restricted to video) produced by an entity flows from the entity's output to one or more entity inputs. Pads should not be confused with physical pins at chip boundaries. A link is a point-to-point oriented connection between two pads, either on the same entity or on different entities. Data flows from a source pad to a sink pad. Links are stored in the source entity. To make backwards graph walk faster, a copy of all links is also stored in the sink entity. The copy is known as a backlink and is only used to help graph traversal. The entity API is made of three functions: - media_entity_init() initializes an entity. The caller must provide an array of pads as well as an estimated number of links. The links array is allocated dynamically and will be reallocated if it grows beyond the initial estimate. - media_entity_cleanup() frees resources allocated for an entity. It must be called during the cleanup phase after unregistering the entity and before freeing it. - media_entity_create_link() creates a link between two entities. An entry in the link array of each entity is allocated and stores pointers to source and sink pads. When a media device is unregistered, all its entities are unregistered automatically. The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>