Linux-libre 4.5-gnu

1 files changed, 844 insertions, 60 deletions

diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index 197f93799..fe485d367 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -23,25 +23,151 @@
 #ifndef _MEDIA_ENTITY_H
 #define _MEDIA_ENTITY_H
 
-#include <linux/bitops.h>
+#include <linux/bitmap.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/media.h>
 
+/* Enums used internally at the media controller to represent graphs */
+
+/**
+ * enum media_gobj_type - type of a graph object
+ *
+ * @MEDIA_GRAPH_ENTITY:		Identify a media entity
+ * @MEDIA_GRAPH_PAD:		Identify a media pad
+ * @MEDIA_GRAPH_LINK:		Identify a media link
+ * @MEDIA_GRAPH_INTF_DEVNODE:	Identify a media Kernel API interface via
+ *				a device node
+ */
+enum media_gobj_type {
+	MEDIA_GRAPH_ENTITY,
+	MEDIA_GRAPH_PAD,
+	MEDIA_GRAPH_LINK,
+	MEDIA_GRAPH_INTF_DEVNODE,
+};
+
+#define MEDIA_BITS_PER_TYPE		8
+#define MEDIA_BITS_PER_ID		(32 - MEDIA_BITS_PER_TYPE)
+#define MEDIA_ID_MASK			 GENMASK_ULL(MEDIA_BITS_PER_ID - 1, 0)
+
+/* Structs to represent the objects that belong to a media graph */
+
+/**
+ * struct media_gobj - Define a graph object.
+ *
+ * @mdev:	Pointer to the struct media_device that owns the object
+ * @id:		Non-zero object ID identifier. The ID should be unique
+ *		inside a media_device, as it is composed by
+ *		%MEDIA_BITS_PER_TYPE to store the type plus
+ *		%MEDIA_BITS_PER_ID to store the ID
+ * @list:	List entry stored in one of the per-type mdev object lists
+ *
+ * All objects on the media graph should have this struct embedded
+ */
+struct media_gobj {
+	struct media_device	*mdev;
+	u32			id;
+	struct list_head	list;
+};
+
+#define MEDIA_ENTITY_ENUM_MAX_DEPTH	16
+
+/**
+ * struct media_entity_enum - An enumeration of media entities.
+ *
+ * @bmap:	Bit map in which each bit represents one entity at struct
+ *		media_entity->internal_idx.
+ * @idx_max:	Number of bits in bmap
+ */
+struct media_entity_enum {
+	unsigned long *bmap;
+	int idx_max;
+};
+
+/**
+ * struct media_entity_graph - Media graph traversal state
+ *
+ * @stack:		Graph traversal stack; the stack contains information
+ *			on the path the media entities to be walked and the
+ *			links through which they were reached.
+ * @ent_enum:		Visited entities
+ * @top:		The top of the stack
+ */
+struct media_entity_graph {
+	struct {
+		struct media_entity *entity;
+		struct list_head *link;
+	} stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
+
+	struct media_entity_enum ent_enum;
+	int top;
+};
+
+/*
+ * struct media_pipeline - Media pipeline related information
+ *
+ * @streaming_count:	Streaming start count - streaming stop count
+ * @graph:		Media graph walk during pipeline start / stop
+ */
 struct media_pipeline {
+	int streaming_count;
+	struct media_entity_graph graph;
 };
 
+/**
+ * struct media_link - A link object part of a media graph.
+ *
+ * @graph_obj:	Embedded structure containing the media object common data
+ * @list:	Linked list associated with an entity or an interface that
+ *		owns the link.
+ * @gobj0:	Part of a union. Used to get the pointer for the first
+ *		graph_object of the link.
+ * @source:	Part of a union. Used only if the first object (gobj0) is
+ *		a pad. In that case, it represents the source pad.
+ * @intf:	Part of a union. Used only if the first object (gobj0) is
+ *		an interface.
+ * @gobj1:	Part of a union. Used to get the pointer for the second
+ *		graph_object of the link.
+ * @source:	Part of a union. Used only if the second object (gobj1) is
+ *		a pad. In that case, it represents the sink pad.
+ * @entity:	Part of a union. Used only if the second object (gobj1) is
+ *		an entity.
+ * @reverse:	Pointer to the link for the reverse direction of a pad to pad
+ *		link.
+ * @flags:	Link flags, as defined in uapi/media.h (MEDIA_LNK_FL_*)
+ * @is_backlink: Indicate if the link is a backlink.
+ */
 struct media_link {
-	struct media_pad *source;	/* Source pad */
-	struct media_pad *sink;		/* Sink pad  */
-	struct media_link *reverse;	/* Link in the reverse direction */
-	unsigned long flags;		/* Link flags (MEDIA_LNK_FL_*) */
+	struct media_gobj graph_obj;
+	struct list_head list;
+	union {
+		struct media_gobj *gobj0;
+		struct media_pad *source;
+		struct media_interface *intf;
+	};
+	union {
+		struct media_gobj *gobj1;
+		struct media_pad *sink;
+		struct media_entity *entity;
+	};
+	struct media_link *reverse;
+	unsigned long flags;
+	bool is_backlink;
 };
 
+/**
+ * struct media_pad - A media pad graph object.
+ *
+ * @graph_obj:	Embedded structure containing the media object common data
+ * @entity:	Entity this pad belongs to
+ * @index:	Pad index in the entity pads array, numbered from 0 to n
+ * @flags:	Pad flags, as defined in uapi/media.h (MEDIA_PAD_FL_*)
+ */
 struct media_pad {
-	struct media_entity *entity;	/* Entity this pad belongs to */
-	u16 index;			/* Pad index in the entity pads array */
-	unsigned long flags;		/* Pad flags (MEDIA_PAD_FL_*) */
+	struct media_gobj graph_obj;	/* must be first field in struct */
+	struct media_entity *entity;
+	u16 index;
+	unsigned long flags;
 };
 
 /**
@@ -60,105 +186,763 @@ struct media_entity_operations {
 	int (*link_validate)(struct media_link *link);
 };
 
+/**
+ * struct media_entity - A media entity graph object.
+ *
+ * @graph_obj:	Embedded structure containing the media object common data.
+ * @name:	Entity name.
+ * @function:	Entity main function, as defined in uapi/media.h
+ *		(MEDIA_ENT_F_*)
+ * @flags:	Entity flags, as defined in uapi/media.h (MEDIA_ENT_FL_*)
+ * @num_pads:	Number of sink and source pads.
+ * @num_links:	Total number of links, forward and back, enabled and disabled.
+ * @num_backlinks: Number of backlinks
+ * @internal_idx: An unique internal entity specific number. The numbers are
+ *		re-used if entities are unregistered or registered again.
+ * @pads:	Pads array with the size defined by @num_pads.
+ * @links:	List of data links.
+ * @ops:	Entity operations.
+ * @stream_count: Stream count for the entity.
+ * @use_count:	Use count for the entity.
+ * @pipe:	Pipeline this entity belongs to.
+ * @info:	Union with devnode information.  Kept just for backward
+ *		compatibility.
+ * @major:	Devnode major number (zero if not applicable). Kept just
+ *		for backward compatibility.
+ * @minor:	Devnode minor number (zero if not applicable). Kept just
+ *		for backward compatibility.
+ *
+ * NOTE: @stream_count and @use_count reference counts must never be
+ * negative, but are signed integers on purpose: a simple WARN_ON(<0) check
+ * can be used to detect reference count bugs that would make them negative.
+ */
 struct media_entity {
-	struct list_head list;
-	struct media_device *parent;	/* Media device this entity belongs to*/
-	u32 id;				/* Entity ID, unique in the parent media
-					 * device context */
-	const char *name;		/* Entity name */
-	u32 type;			/* Entity type (MEDIA_ENT_T_*) */
-	u32 revision;			/* Entity revision, driver specific */
-	unsigned long flags;		/* Entity flags (MEDIA_ENT_FL_*) */
-	u32 group_id;			/* Entity group ID */
-
-	u16 num_pads;			/* Number of sink and source pads */
-	u16 num_links;			/* Number of existing links, both
-					 * enabled and disabled */
-	u16 num_backlinks;		/* Number of backlinks */
-	u16 max_links;			/* Maximum number of links */
-
-	struct media_pad *pads;		/* Pads array (num_pads elements) */
-	struct media_link *links;	/* Links array (max_links elements)*/
-
-	const struct media_entity_operations *ops;	/* Entity operations */
+	struct media_gobj graph_obj;	/* must be first field in struct */
+	const char *name;
+	u32 function;
+	unsigned long flags;
+
+	u16 num_pads;
+	u16 num_links;
+	u16 num_backlinks;
+	int internal_idx;
+
+	struct media_pad *pads;
+	struct list_head links;
+
+	const struct media_entity_operations *ops;
 
 	/* Reference counts must never be negative, but are signed integers on
 	 * purpose: a simple WARN_ON(<0) check can be used to detect reference
 	 * count bugs that would make them negative.
 	 */
-	int stream_count;		/* Stream count for the entity. */
-	int use_count;			/* Use count for the entity. */
+	int stream_count;
+	int use_count;
 
-	struct media_pipeline *pipe;	/* Pipeline this entity belongs to. */
+	struct media_pipeline *pipe;
 
 	union {
-		/* Node specifications */
 		struct {
 			u32 major;
 			u32 minor;
 		} dev;
-
-		/* Sub-device specifications */
-		/* Nothing needed yet */
 	} info;
 };
 
-static inline u32 media_entity_type(struct media_entity *entity)
+/**
+ * struct media_interface - A media interface graph object.
+ *
+ * @graph_obj:		embedded graph object
+ * @links:		List of links pointing to graph entities
+ * @type:		Type of the interface as defined in the
+ *			uapi/media/media.h header, e. g.
+ *			MEDIA_INTF_T_*
+ * @flags:		Interface flags as defined in uapi/media/media.h
+ */
+struct media_interface {
+	struct media_gobj		graph_obj;
+	struct list_head		links;
+	u32				type;
+	u32				flags;
+};
+
+/**
+ * struct media_intf_devnode - A media interface via a device node.
+ *
+ * @intf:	embedded interface object
+ * @major:	Major number of a device node
+ * @minor:	Minor number of a device node
+ */
+struct media_intf_devnode {
+	struct media_interface		intf;
+
+	/* Should match the fields at media_v2_intf_devnode */
+	u32				major;
+	u32				minor;
+};
+
+/**
+ * media_entity_id() - return the media entity graph object id
+ *
+ * @entity:	pointer to entity
+ */
+static inline u32 media_entity_id(struct media_entity *entity)
 {
-	return entity->type & MEDIA_ENT_TYPE_MASK;
+	return entity->graph_obj.id;
 }
 
-static inline u32 media_entity_subtype(struct media_entity *entity)
+/**
+ * media_type() - return the media object type
+ *
+ * @gobj:	pointer to the media graph object
+ */
+static inline enum media_gobj_type media_type(struct media_gobj *gobj)
 {
-	return entity->type & MEDIA_ENT_SUBTYPE_MASK;
+	return gobj->id >> MEDIA_BITS_PER_ID;
 }
 
-#define MEDIA_ENTITY_ENUM_MAX_DEPTH	16
-#define MEDIA_ENTITY_ENUM_MAX_ID	64
+/**
+ * media_id() - return the media object ID
+ *
+ * @gobj:	pointer to the media graph object
+ */
+static inline u32 media_id(struct media_gobj *gobj)
+{
+	return gobj->id & MEDIA_ID_MASK;
+}
 
-/*
- * The number of pads can't be bigger than the number of entities,
- * as the worse-case scenario is to have one entity linked up to
- * MEDIA_ENTITY_ENUM_MAX_ID - 1 entities.
+/**
+ * media_gobj_gen_id() - encapsulates type and ID on at the object ID
+ *
+ * @type:	object type as define at enum &media_gobj_type.
+ * @local_id:	next ID, from struct &media_device.@id.
  */
-#define MEDIA_ENTITY_MAX_PADS		(MEDIA_ENTITY_ENUM_MAX_ID - 1)
+static inline u32 media_gobj_gen_id(enum media_gobj_type type, u64 local_id)
+{
+	u32 id;
 
-struct media_entity_graph {
-	struct {
-		struct media_entity *entity;
-		int link;
-	} stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
+	id = type << MEDIA_BITS_PER_ID;
+	id |= local_id & MEDIA_ID_MASK;
 
-	DECLARE_BITMAP(entities, MEDIA_ENTITY_ENUM_MAX_ID);
-	int top;
-};
+	return id;
+}
+
+/**
+ * is_media_entity_v4l2_io() - identify if the entity main function
+ *			       is a V4L2 I/O
+ *
+ * @entity:	pointer to entity
+ *
+ * Return: true if the entity main function is one of the V4L2 I/O types
+ *	(video, VBI or SDR radio); false otherwise.
+ */
+static inline bool is_media_entity_v4l2_io(struct media_entity *entity)
+{
+	if (!entity)
+		return false;
+
+	switch (entity->function) {
+	case MEDIA_ENT_F_IO_V4L:
+	case MEDIA_ENT_F_IO_VBI:
+	case MEDIA_ENT_F_IO_SWRADIO:
+		return true;
+	default:
+		return false;
+	}
+}
+
+/**
+ * is_media_entity_v4l2_subdev - return true if the entity main function is
+ *				 associated with the V4L2 API subdev usage
+ *
+ * @entity:	pointer to entity
+ *
+ * This is an ancillary function used by subdev-based V4L2 drivers.
+ * It checks if the entity function is one of functions used by a V4L2 subdev,
+ * e. g. camera-relatef functions, analog TV decoder, TV tuner, V4L2 DSPs.
+ */
+static inline bool is_media_entity_v4l2_subdev(struct media_entity *entity)
+{
+	if (!entity)
+		return false;
+
+	switch (entity->function) {
+	case MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN:
+	case MEDIA_ENT_F_CAM_SENSOR:
+	case MEDIA_ENT_F_FLASH:
+	case MEDIA_ENT_F_LENS:
+	case MEDIA_ENT_F_ATV_DECODER:
+	case MEDIA_ENT_F_TUNER:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
+/**
+ * __media_entity_enum_init - Initialise an entity enumeration
+ *
+ * @ent_enum: Entity enumeration to be initialised
+ * @idx_max: Maximum number of entities in the enumeration
+ *
+ * Return: Returns zero on success or a negative error code.
+ */
+__must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
+					  int idx_max);
+
+/**
+ * media_entity_enum_cleanup - Release resources of an entity enumeration
+ *
+ * @ent_enum: Entity enumeration to be released
+ */
+void media_entity_enum_cleanup(struct media_entity_enum *ent_enum);
+
+/**
+ * media_entity_enum_zero - Clear the entire enum
+ *
+ * @ent_enum: Entity enumeration to be cleared
+ */
+static inline void media_entity_enum_zero(struct media_entity_enum *ent_enum)
+{
+	bitmap_zero(ent_enum->bmap, ent_enum->idx_max);
+}
+
+/**
+ * media_entity_enum_set - Mark a single entity in the enum
+ *
+ * @ent_enum: Entity enumeration
+ * @entity: Entity to be marked
+ */
+static inline void media_entity_enum_set(struct media_entity_enum *ent_enum,
+					 struct media_entity *entity)
+{
+	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
+		return;
+
+	__set_bit(entity->internal_idx, ent_enum->bmap);
+}
+
+/**
+ * media_entity_enum_clear - Unmark a single entity in the enum
+ *
+ * @ent_enum: Entity enumeration
+ * @entity: Entity to be unmarked
+ */
+static inline void media_entity_enum_clear(struct media_entity_enum *ent_enum,
+					   struct media_entity *entity)
+{
+	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
+		return;
 
-int media_entity_init(struct media_entity *entity, u16 num_pads,
-		struct media_pad *pads, u16 extra_links);
-void media_entity_cleanup(struct media_entity *entity);
+	__clear_bit(entity->internal_idx, ent_enum->bmap);
+}
+
+/**
+ * media_entity_enum_test - Test whether the entity is marked
+ *
+ * @ent_enum: Entity enumeration
+ * @entity: Entity to be tested
+ *
+ * Returns true if the entity was marked.
+ */
+static inline bool media_entity_enum_test(struct media_entity_enum *ent_enum,
+					  struct media_entity *entity)
+{
+	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
+		return true;
+
+	return test_bit(entity->internal_idx, ent_enum->bmap);
+}
+
+/**
+ * media_entity_enum_test - Test whether the entity is marked, and mark it
+ *
+ * @ent_enum: Entity enumeration
+ * @entity: Entity to be tested
+ *
+ * Returns true if the entity was marked, and mark it before doing so.
+ */
+static inline bool
+media_entity_enum_test_and_set(struct media_entity_enum *ent_enum,
+			       struct media_entity *entity)
+{
+	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
+		return true;
+
+	return __test_and_set_bit(entity->internal_idx, ent_enum->bmap);
+}
+
+/**
+ * media_entity_enum_empty - Test whether the entire enum is empty
+ *
+ * @ent_enum: Entity enumeration
+ *
+ * Returns true if the entity was marked.
+ */
+static inline bool media_entity_enum_empty(struct media_entity_enum *ent_enum)
+{
+	return bitmap_empty(ent_enum->bmap, ent_enum->idx_max);
+}
+
+/**
+ * media_entity_enum_intersects - Test whether two enums intersect
+ *
+ * @ent_enum1: First entity enumeration
+ * @ent_enum2: Second entity enumeration
+ *
+ * Returns true if entity enumerations e and f intersect, otherwise false.
+ */
+static inline bool media_entity_enum_intersects(
+	struct media_entity_enum *ent_enum1,
+	struct media_entity_enum *ent_enum2)
+{
+	WARN_ON(ent_enum1->idx_max != ent_enum2->idx_max);
+
+	return bitmap_intersects(ent_enum1->bmap, ent_enum2->bmap,
+				 min(ent_enum1->idx_max, ent_enum2->idx_max));
+}
+
+#define gobj_to_entity(gobj) \
+		container_of(gobj, struct media_entity, graph_obj)
+
+#define gobj_to_pad(gobj) \
+		container_of(gobj, struct media_pad, graph_obj)
+
+#define gobj_to_link(gobj) \
+		container_of(gobj, struct media_link, graph_obj)
+
+#define gobj_to_link(gobj) \
+		container_of(gobj, struct media_link, graph_obj)
+
+#define gobj_to_pad(gobj) \
+		container_of(gobj, struct media_pad, graph_obj)
+
+#define gobj_to_intf(gobj) \
+		container_of(gobj, struct media_interface, graph_obj)
+
+#define intf_to_devnode(intf) \
+		container_of(intf, struct media_intf_devnode, intf)
+
+/**
+ *  media_gobj_create - Initialize a graph object
+ *
+ * @mdev:	Pointer to the media_device that contains the object
+ * @type:	Type of the object
+ * @gobj:	Pointer to the graph object
+ *
+ * This routine initializes the embedded struct media_gobj inside a
+ * media graph object. It is called automatically if media_*_create()
+ * calls are used. However, if the object (entity, link, pad, interface)
+ * is embedded on some other object, this function should be called before
+ * registering the object at the media controller.
+ */
+void media_gobj_create(struct media_device *mdev,
+		    enum media_gobj_type type,
+		    struct media_gobj *gobj);
+
+/**
+ *  media_gobj_destroy - Stop using a graph object on a media device
+ *
+ * @gobj:	Pointer to the graph object
+ *
+ * This should be called by all routines like media_device_unregister()
+ * that remove/destroy media graph objects.
+ */
+void media_gobj_destroy(struct media_gobj *gobj);
+
+/**
+ * media_entity_pads_init() - Initialize the entity pads
+ *
+ * @entity:	entity where the pads belong
+ * @num_pads:	total number of sink and source pads
+ * @pads:	Array of @num_pads pads.
+ *
+ * The pads array is managed by the entity driver and passed to
+ * media_entity_pads_init() where its pointer will be stored in the entity
+ * structure.
+ *
+ * If no pads are needed, drivers could either directly fill
+ * &media_entity->@num_pads with 0 and &media_entity->@pads with NULL or call
+ * this function that will do the same.
+ *
+ * As the number of pads is known in advance, the pads array is not allocated
+ * dynamically but is managed by the entity driver. Most drivers will embed the
+ * pads array in a driver-specific structure, avoiding dynamic allocation.
+ *
+ * Drivers must set the direction of every pad in the pads array before calling
+ * media_entity_pads_init(). The function will initialize the other pads fields.
+ */
+int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
+		      struct media_pad *pads);
+
+/**
+ * media_entity_cleanup() - free resources associated with an entity
+ *
+ * @entity:	entity where the pads belong
+ *
+ * This function must be called during the cleanup phase after unregistering
+ * the entity (currently, it does nothing).
+ */
+static inline void media_entity_cleanup(struct media_entity *entity) {};
+
+/**
+ * media_create_pad_link() - creates a link between two entities.
+ *
+ * @source:	pointer to &media_entity of the source pad.
+ * @source_pad:	number of the source pad in the pads array
+ * @sink:	pointer to &media_entity of the sink pad.
+ * @sink_pad:	number of the sink pad in the pads array.
+ * @flags:	Link flags, as defined in include/uapi/linux/media.h.
+ *
+ * Valid values for flags:
+ * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
+ *	used to transfer media data. When two or more links target a sink pad,
+ *	only one of them can be enabled at a time.
+ *
+ * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
+ *	be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
+ *	%MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
+ *	always enabled.
+ *
+ * NOTE:
+ *
+ * Before calling this function, media_entity_pads_init() and
+ * media_device_register_entity() should be called previously for both ends.
+ */
+__must_check int media_create_pad_link(struct media_entity *source,
+			u16 source_pad, struct media_entity *sink,
+			u16 sink_pad, u32 flags);
+
+/**
+ * media_create_pad_links() - creates a link between two entities.
+ *
+ * @mdev: Pointer to the media_device that contains the object
+ * @source_function: Function of the source entities. Used only if @source is
+ *	NULL.
+ * @source: pointer to &media_entity of the source pad. If NULL, it will use
+ * 	all entities that matches the @sink_function.
+ * @source_pad: number of the source pad in the pads array
+ * @sink_function: Function of the sink entities. Used only if @sink is NULL.
+ * @sink: pointer to &media_entity of the sink pad. If NULL, it will use
+ * 	all entities that matches the @sink_function.
+ * @sink_pad: number of the sink pad in the pads array.
+ * @flags: Link flags, as defined in include/uapi/linux/media.h.
+ * @allow_both_undefined: if true, then both @source and @sink can be NULL.
+ *	In such case, it will create a crossbar between all entities that
+ *	matches @source_function to all entities that matches @sink_function.
+ *	If false, it will return 0 and won't create any link if both @source
+ *	and @sink are NULL.
+ *
+ * Valid values for flags:
+ * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
+ *	used to transfer media data. If multiple links are created and this
+ *	flag is passed as an argument, only the first created link will have
+ *	this flag.
+ *
+ * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
+ *	be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
+ *	%MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
+ *	always enabled.
+ *
+ * It is common for some devices to have multiple source and/or sink entities
+ * of the same type that should be linked. While media_create_pad_link()
+ * creates link by link, this function is meant to allow 1:n, n:1 and even
+ * cross-bar (n:n) links.
+ *
+ * NOTE: Before calling this function, media_entity_pads_init() and
+ * media_device_register_entity() should be called previously for the entities
+ * to be linked.
+ */
+int media_create_pad_links(const struct media_device *mdev,
+			   const u32 source_function,
+			   struct media_entity *source,
+			   const u16 source_pad,
+			   const u32 sink_function,
+			   struct media_entity *sink,
+			   const u16 sink_pad,
+			   u32 flags,
+			   const bool allow_both_undefined);
 
-int media_entity_create_link(struct media_entity *source, u16 source_pad,
-		struct media_entity *sink, u16 sink_pad, u32 flags);
 void __media_entity_remove_links(struct media_entity *entity);
+
+/**
+ * media_entity_remove_links() - remove all links associated with an entity
+ *
+ * @entity:	pointer to &media_entity
+ *
+ * Note: this is called automatically when an entity is unregistered via
+ * media_device_register_entity().
+ */
 void media_entity_remove_links(struct media_entity *entity);
 
+/**
+ * __media_entity_setup_link - Configure a media link without locking
+ * @link: The link being configured
+ * @flags: Link configuration flags
+ *
+ * The bulk of link setup is handled by the two entities connected through the
+ * link. This function notifies both entities of the link configuration change.
+ *
+ * If the link is immutable or if the current and new configuration are
+ * identical, return immediately.
+ *
+ * The user is expected to hold link->source->parent->mutex. If not,
+ * media_entity_setup_link() should be used instead.
+ */
 int __media_entity_setup_link(struct media_link *link, u32 flags);
+
+/**
+ * media_entity_setup_link() - changes the link flags properties in runtime
+ *
+ * @link:	pointer to &media_link
+ * @flags:	the requested new link flags
+ *
+ * The only configurable property is the %MEDIA_LNK_FL_ENABLED link flag
+ * flag to enable/disable a link. Links marked with the
+ * %MEDIA_LNK_FL_IMMUTABLE link flag can not be enabled or disabled.
+ *
+ * When a link is enabled or disabled, the media framework calls the
+ * link_setup operation for the two entities at the source and sink of the
+ * link, in that order. If the second link_setup call fails, another
+ * link_setup call is made on the first entity to restore the original link
+ * flags.
+ *
+ * Media device drivers can be notified of link setup operations by setting the
+ * media_device::link_notify pointer to a callback function. If provided, the
+ * notification callback will be called before enabling and after disabling
+ * links.
+ *
+ * Entity drivers must implement the link_setup operation if any of their links
+ * is non-immutable. The operation must either configure the hardware or store
+ * the configuration information to be applied later.
+ *
+ * Link configuration must not have any side effect on other links. If an
+ * enabled link at a sink pad prevents another link at the same pad from
+ * being enabled, the link_setup operation must return -EBUSY and can't
+ * implicitly disable the first enabled link.
+ *
+ * NOTE: the valid values of the flags for the link is the same as described
+ * on media_create_pad_link(), for pad to pad links or the same as described
+ * on media_create_intf_link(), for interface to entity links.
+ */
 int media_entity_setup_link(struct media_link *link, u32 flags);
+
+/**
+ * media_entity_find_link - Find a link between two pads
+ * @source: Source pad
+ * @sink: Sink pad
+ *
+ * Return a pointer to the link between the two entities. If no such link
+ * exists, return NULL.
+ */
 struct media_link *media_entity_find_link(struct media_pad *source,
 		struct media_pad *sink);
+
+/**
+ * media_entity_remote_pad - Find the pad at the remote end of a link
+ * @pad: Pad at the local end of the link
+ *
+ * Search for a remote pad connected to the given pad by iterating over all
+ * links originating or terminating at that pad until an enabled link is found.
+ *
+ * Return a pointer to the pad at the remote end of the first found enabled
+ * link, or NULL if no enabled link has been found.
+ */
 struct media_pad *media_entity_remote_pad(struct media_pad *pad);
 
+/**
+ * media_entity_get - Get a reference to the parent module
+ *
+ * @entity: The entity
+ *
+ * Get a reference to the parent media device module.
+ *
+ * The function will return immediately if @entity is NULL.
+ *
+ * Return a pointer to the entity on success or NULL on failure.
+ */
 struct media_entity *media_entity_get(struct media_entity *entity);
+
+__must_check int media_entity_graph_walk_init(
+	struct media_entity_graph *graph, struct media_device *mdev);
+
+/**
+ * media_entity_graph_walk_cleanup - Release resources used by graph walk.
+ *
+ * @graph: Media graph structure that will be used to walk the graph
+ */
+void media_entity_graph_walk_cleanup(struct media_entity_graph *graph);
+
+/**
+ * media_entity_put - Release the reference to the parent module
+ *
+ * @entity: The entity
+ *
+ * Release the reference count acquired by media_entity_get().
+ *
+ * The function will return immediately if @entity is NULL.
+ */
 void media_entity_put(struct media_entity *entity);
 
+/**
+ * media_entity_graph_walk_start - Start walking the media graph at a given entity
+ * @graph: Media graph structure that will be used to walk the graph
+ * @entity: Starting entity
+ *
+ * Before using this function, media_entity_graph_walk_init() must be
+ * used to allocate resources used for walking the graph. This
+ * function initializes the graph traversal structure to walk the
+ * entities graph starting at the given entity. The traversal
+ * structure must not be modified by the caller during graph
+ * traversal. After the graph walk, the resources must be released
+ * using media_entity_graph_walk_cleanup().
+ */
 void media_entity_graph_walk_start(struct media_entity_graph *graph,
-		struct media_entity *entity);
+				   struct media_entity *entity);
+
+/**
+ * media_entity_graph_walk_next - Get the next entity in the graph
+ * @graph: Media graph structure
+ *
+ * Perform a depth-first traversal of the given media entities graph.
+ *
+ * The graph structure must have been previously initialized with a call to
+ * media_entity_graph_walk_start().
+ *
+ * Return the next entity in the graph or NULL if the whole graph have been
+ * traversed.
+ */
 struct media_entity *
 media_entity_graph_walk_next(struct media_entity_graph *graph);
+
+/**
+ * media_entity_pipeline_start - Mark a pipeline as streaming
+ * @entity: Starting entity
+ * @pipe: Media pipeline to be assigned to all entities in the pipeline.
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as streaming. The given pipeline object is assigned to
+ * every entity in the pipeline and stored in the media_entity pipe field.
+ *
+ * Calls to this function can be nested, in which case the same number of
+ * media_entity_pipeline_stop() calls will be required to stop streaming. The
+ * pipeline pointer must be identical for all nested calls to
+ * media_entity_pipeline_start().
+ */
 __must_check int media_entity_pipeline_start(struct media_entity *entity,
 					     struct media_pipeline *pipe);
+
+/**
+ * media_entity_pipeline_stop - Mark a pipeline as not streaming
+ * @entity: Starting entity
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as not streaming. The media_entity pipe field is
+ * reset to NULL.
+ *
+ * If multiple calls to media_entity_pipeline_start() have been made, the same
+ * number of calls to this function are required to mark the pipeline as not
+ * streaming.
+ */
 void media_entity_pipeline_stop(struct media_entity *entity);
 
+/**
+ * media_devnode_create() - creates and initializes a device node interface
+ *
+ * @mdev:	pointer to struct &media_device
+ * @type:	type of the interface, as given by MEDIA_INTF_T_* macros
+ *		as defined in the uapi/media/media.h header.
+ * @flags:	Interface flags as defined in uapi/media/media.h.
+ * @major:	Device node major number.
+ * @minor:	Device node minor number.
+ *
+ * Return: if succeeded, returns a pointer to the newly allocated
+ *	&media_intf_devnode pointer.
+ */
+struct media_intf_devnode *
+__must_check media_devnode_create(struct media_device *mdev,
+				  u32 type, u32 flags,
+				  u32 major, u32 minor);
+/**
+ * media_devnode_remove() - removes a device node interface
+ *
+ * @devnode:	pointer to &media_intf_devnode to be freed.
+ *
+ * When a device node interface is removed, all links to it are automatically
+ * removed.
+ */
+void media_devnode_remove(struct media_intf_devnode *devnode);
+struct media_link *
+
+/**
+ * media_create_intf_link() - creates a link between an entity and an interface
+ *
+ * @entity:	pointer to %media_entity
+ * @intf:	pointer to %media_interface
+ * @flags:	Link flags, as defined in include/uapi/linux/media.h.
+ *
+ *
+ * Valid values for flags:
+ * The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
+ *	the entity hardware. That's the default value for interfaces. An
+ *	interface may be disabled if the hardware is busy due to the usage
+ *	of some other interface that it is currently controlling the hardware.
+ *	A typical example is an hybrid TV device that handle only one type of
+ *	stream on a given time. So, when the digital TV is streaming,
+ *	the V4L2 interfaces won't be enabled, as such device is not able to
+ *	also stream analog TV or radio.
+ *
+ * Note:
+ *
+ * Before calling this function, media_devnode_create() should be called for
+ * the interface and media_device_register_entity() should be called for the
+ * interface that will be part of the link.
+ */
+__must_check media_create_intf_link(struct media_entity *entity,
+				    struct media_interface *intf,
+				    u32 flags);
+/**
+ * __media_remove_intf_link() - remove a single interface link
+ *
+ * @link:	pointer to &media_link.
+ *
+ * Note: this is an unlocked version of media_remove_intf_link()
+ */
+void __media_remove_intf_link(struct media_link *link);
+
+/**
+ * media_remove_intf_link() - remove a single interface link
+ *
+ * @link:	pointer to &media_link.
+ *
+ * Note: prefer to use this one, instead of __media_remove_intf_link()
+ */
+void media_remove_intf_link(struct media_link *link);
+
+/**
+ * __media_remove_intf_links() - remove all links associated with an interface
+ *
+ * @intf:	pointer to &media_interface
+ *
+ * Note: this is an unlocked version of media_remove_intf_links().
+ */
+void __media_remove_intf_links(struct media_interface *intf);
+
+/**
+ * media_remove_intf_links() - remove all links associated with an interface
+ *
+ * @intf:	pointer to &media_interface
+ *
+ * Notes:
+ *
+ * this is called automatically when an entity is unregistered via
+ * media_device_register_entity() and by media_devnode_remove().
+ *
+ * Prefer to use this one, instead of __media_remove_intf_links().
+ */
+void media_remove_intf_links(struct media_interface *intf);
+
 #define media_entity_call(entity, operation, args...)			\
 	(((entity)->ops && (entity)->ops->operation) ?			\
 	 (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)