1 files changed, 828 insertions, 187 deletions

diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index f40f41977142..9519a537bfa2 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -9,27 +9,12 @@
  */
 
 #include <linux/bitmap.h>
+#include <linux/list.h>
 #include <linux/property.h>
 #include <linux/slab.h>
 #include <media/media-entity.h>
 #include <media/media-device.h>
 
-static inline const char *gobj_type(enum media_gobj_type type)
-{
-	switch (type) {
-	case MEDIA_GRAPH_ENTITY:
-		return "entity";
-	case MEDIA_GRAPH_PAD:
-		return "pad";
-	case MEDIA_GRAPH_LINK:
-		return "link";
-	case MEDIA_GRAPH_INTF_DEVNODE:
-		return "intf-devnode";
-	default:
-		return "unknown";
-	}
-}
-
 static inline const char *intf_type(struct media_interface *intf)
 {
 	switch (intf->type) {
@@ -60,25 +45,39 @@ static inline const char *intf_type(struct media_interface *intf)
 	}
 };
 
-__must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
-					  int idx_max)
+static inline const char *link_type_name(struct media_link *link)
 {
-	idx_max = ALIGN(idx_max, BITS_PER_LONG);
-	ent_enum->bmap = kcalloc(idx_max / BITS_PER_LONG, sizeof(long),
-				 GFP_KERNEL);
+	switch (link->flags & MEDIA_LNK_FL_LINK_TYPE) {
+	case MEDIA_LNK_FL_DATA_LINK:
+		return "data";
+	case MEDIA_LNK_FL_INTERFACE_LINK:
+		return "interface";
+	case MEDIA_LNK_FL_ANCILLARY_LINK:
+		return "ancillary";
+	default:
+		return "unknown";
+	}
+}
+
+__must_check int media_entity_enum_init(struct media_entity_enum *ent_enum,
+					struct media_device *mdev)
+{
+	int idx_max;
+
+	idx_max = ALIGN(mdev->entity_internal_idx_max + 1, BITS_PER_LONG);
+	ent_enum->bmap = bitmap_zalloc(idx_max, GFP_KERNEL);
 	if (!ent_enum->bmap)
 		return -ENOMEM;
 
-	bitmap_zero(ent_enum->bmap, idx_max);
 	ent_enum->idx_max = idx_max;
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__media_entity_enum_init);
+EXPORT_SYMBOL_GPL(media_entity_enum_init);
 
 void media_entity_enum_cleanup(struct media_entity_enum *ent_enum)
 {
-	kfree(ent_enum->bmap);
+	bitmap_free(ent_enum->bmap);
 }
 EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
 
@@ -107,9 +106,7 @@ static void dev_dbg_obj(const char *event_name,  struct media_gobj *gobj)
 
 		dev_dbg(gobj->mdev->dev,
 			"%s id %u: %s link id %u ==> id %u\n",
-			event_name, media_id(gobj),
-			media_type(link->gobj0) == MEDIA_GRAPH_PAD ?
-				"data" : "interface",
+			event_name, media_id(gobj), link_type_name(link),
 			media_id(link->gobj0),
 			media_id(link->gobj1));
 		break;
@@ -198,7 +195,9 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
 			   struct media_pad *pads)
 {
 	struct media_device *mdev = entity->graph_obj.mdev;
-	unsigned int i;
+	struct media_pad *iter;
+	unsigned int i = 0;
+	int ret = 0;
 
 	if (num_pads >= MEDIA_ENTITY_MAX_PADS)
 		return -E2BIG;
@@ -209,18 +208,30 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
 	if (mdev)
 		mutex_lock(&mdev->graph_mutex);
 
-	for (i = 0; i < num_pads; i++) {
-		pads[i].entity = entity;
-		pads[i].index = i;
+	media_entity_for_each_pad(entity, iter) {
+		iter->entity = entity;
+		iter->index = i++;
+
+		if (hweight32(iter->flags & (MEDIA_PAD_FL_SINK |
+					     MEDIA_PAD_FL_SOURCE)) != 1) {
+			ret = -EINVAL;
+			break;
+		}
+
 		if (mdev)
 			media_gobj_create(mdev, MEDIA_GRAPH_PAD,
-					&entity->pads[i].graph_obj);
+					  &iter->graph_obj);
+	}
+
+	if (ret && mdev) {
+		media_entity_for_each_pad(entity, iter)
+			media_gobj_destroy(&iter->graph_obj);
 	}
 
 	if (mdev)
 		mutex_unlock(&mdev->graph_mutex);
 
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(media_entity_pads_init);
 
@@ -228,6 +239,46 @@ EXPORT_SYMBOL_GPL(media_entity_pads_init);
  * Graph traversal
  */
 
+/**
+ * media_entity_has_pad_interdep - Check interdependency between two pads
+ *
+ * @entity: The entity
+ * @pad0: The first pad index
+ * @pad1: The second pad index
+ *
+ * This function checks the interdependency inside the entity between @pad0
+ * and @pad1. If two pads are interdependent they are part of the same pipeline
+ * and enabling one of the pads means that the other pad will become "locked"
+ * and doesn't allow configuration changes.
+ *
+ * This function uses the &media_entity_operations.has_pad_interdep() operation
+ * to check the dependency inside the entity between @pad0 and @pad1. If the
+ * has_pad_interdep operation is not implemented, all pads of the entity are
+ * considered to be interdependent.
+ *
+ * One of @pad0 and @pad1 must be a sink pad and the other one a source pad.
+ * The function returns false if both pads are sinks or sources.
+ *
+ * The caller must hold entity->graph_obj.mdev->mutex.
+ *
+ * Return: true if the pads are connected internally and false otherwise.
+ */
+static bool media_entity_has_pad_interdep(struct media_entity *entity,
+					  unsigned int pad0, unsigned int pad1)
+{
+	if (pad0 >= entity->num_pads || pad1 >= entity->num_pads)
+		return false;
+
+	if (entity->pads[pad0].flags & entity->pads[pad1].flags &
+	    (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE))
+		return false;
+
+	if (!entity->ops || !entity->ops->has_pad_interdep)
+		return true;
+
+	return entity->ops->has_pad_interdep(entity, pad0, pad1);
+}
+
 static struct media_entity *
 media_entity_other(struct media_entity *entity, struct media_link *link)
 {
@@ -270,7 +321,7 @@ static struct media_entity *stack_pop(struct media_graph *graph)
  *
  * Reserve resources for graph walk in media device's current
  * state. The memory must be released using
- * media_graph_walk_free().
+ * media_graph_walk_cleanup().
  *
  * Returns error on failure, zero on success.
  */
@@ -313,6 +364,12 @@ static void media_graph_walk_iter(struct media_graph *graph)
 
 	link = list_entry(link_top(graph), typeof(*link), list);
 
+	/* If the link is not a data link, don't follow it */
+	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
+		link_top(graph) = link_top(graph)->next;
+		return;
+	}
+
 	/* The link is not enabled so we do not follow. */
 	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
 		link_top(graph) = link_top(graph)->next;
@@ -366,137 +423,476 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)
 }
 EXPORT_SYMBOL_GPL(media_graph_walk_next);
 
-int media_entity_get_fwnode_pad(struct media_entity *entity,
-				struct fwnode_handle *fwnode,
-				unsigned long direction_flags)
+/* -----------------------------------------------------------------------------
+ * Pipeline management
+ */
+
+/*
+ * The pipeline traversal stack stores pads that are reached during graph
+ * traversal, with a list of links to be visited to continue the traversal.
+ * When a new pad is reached, an entry is pushed on the top of the stack and
+ * points to the incoming pad and the first link of the entity.
+ *
+ * To find further pads in the pipeline, the traversal algorithm follows
+ * internal pad dependencies in the entity, and then links in the graph. It
+ * does so by iterating over all links of the entity, and following enabled
+ * links that originate from a pad that is internally connected to the incoming
+ * pad, as reported by the media_entity_has_pad_interdep() function.
+ */
+
+/**
+ * struct media_pipeline_walk_entry - Entry in the pipeline traversal stack
+ *
+ * @pad: The media pad being visited
+ * @links: Links left to be visited
+ */
+struct media_pipeline_walk_entry {
+	struct media_pad *pad;
+	struct list_head *links;
+};
+
+/**
+ * struct media_pipeline_walk - State used by the media pipeline traversal
+ *				algorithm
+ *
+ * @mdev: The media device
+ * @stack: Depth-first search stack
+ * @stack.size: Number of allocated entries in @stack.entries
+ * @stack.top: Index of the top stack entry (-1 if the stack is empty)
+ * @stack.entries: Stack entries
+ */
+struct media_pipeline_walk {
+	struct media_device *mdev;
+
+	struct {
+		unsigned int size;
+		int top;
+		struct media_pipeline_walk_entry *entries;
+	} stack;
+};
+
+#define MEDIA_PIPELINE_STACK_GROW_STEP		16
+
+static struct media_pipeline_walk_entry *
+media_pipeline_walk_top(struct media_pipeline_walk *walk)
 {
-	struct fwnode_endpoint endpoint;
-	unsigned int i;
+	return &walk->stack.entries[walk->stack.top];
+}
+
+static bool media_pipeline_walk_empty(struct media_pipeline_walk *walk)
+{
+	return walk->stack.top == -1;
+}
+
+/* Increase the stack size by MEDIA_PIPELINE_STACK_GROW_STEP elements. */
+static int media_pipeline_walk_resize(struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entries;
+	unsigned int new_size;
+
+	/* Safety check, to avoid stack overflows in case of bugs. */
+	if (walk->stack.size >= 256)
+		return -E2BIG;
+
+	new_size = walk->stack.size + MEDIA_PIPELINE_STACK_GROW_STEP;
+
+	entries = krealloc(walk->stack.entries,
+			   new_size * sizeof(*walk->stack.entries),
+			   GFP_KERNEL);
+	if (!entries)
+		return -ENOMEM;
+
+	walk->stack.entries = entries;
+	walk->stack.size = new_size;
+
+	return 0;
+}
+
+/* Push a new entry on the stack. */
+static int media_pipeline_walk_push(struct media_pipeline_walk *walk,
+				    struct media_pad *pad)
+{
+	struct media_pipeline_walk_entry *entry;
 	int ret;
 
-	if (!entity->ops || !entity->ops->get_fwnode_pad) {
-		for (i = 0; i < entity->num_pads; i++) {
-			if (entity->pads[i].flags & direction_flags)
-				return i;
+	if (walk->stack.top + 1 >= walk->stack.size) {
+		ret = media_pipeline_walk_resize(walk);
+		if (ret)
+			return ret;
+	}
+
+	walk->stack.top++;
+	entry = media_pipeline_walk_top(walk);
+	entry->pad = pad;
+	entry->links = pad->entity->links.next;
+
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: pushed entry %u: '%s':%u\n",
+		walk->stack.top, pad->entity->name, pad->index);
+
+	return 0;
+}
+
+/*
+ * Move the top entry link cursor to the next link. If all links of the entry
+ * have been visited, pop the entry itself. Return true if the entry has been
+ * popped.
+ */
+static bool media_pipeline_walk_pop(struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entry;
+
+	if (WARN_ON(walk->stack.top < 0))
+		return false;
+
+	entry = media_pipeline_walk_top(walk);
+
+	if (entry->links->next == &entry->pad->entity->links) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: entry %u has no more links, popping\n",
+			walk->stack.top);
+
+		walk->stack.top--;
+		return true;
+	}
+
+	entry->links = entry->links->next;
+
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: moved entry %u to next link\n",
+		walk->stack.top);
+
+	return false;
+}
+
+/* Free all memory allocated while walking the pipeline. */
+static void media_pipeline_walk_destroy(struct media_pipeline_walk *walk)
+{
+	kfree(walk->stack.entries);
+}
+
+/* Add a pad to the pipeline and push it to the stack. */
+static int media_pipeline_add_pad(struct media_pipeline *pipe,
+				  struct media_pipeline_walk *walk,
+				  struct media_pad *pad)
+{
+	struct media_pipeline_pad *ppad;
+
+	list_for_each_entry(ppad, &pipe->pads, list) {
+		if (ppad->pad == pad) {
+			dev_dbg(pad->graph_obj.mdev->dev,
+				"media pipeline: already contains pad '%s':%u\n",
+				pad->entity->name, pad->index);
+			return 0;
 		}
+	}
 
-		return -ENXIO;
+	ppad = kzalloc(sizeof(*ppad), GFP_KERNEL);
+	if (!ppad)
+		return -ENOMEM;
+
+	ppad->pipe = pipe;
+	ppad->pad = pad;
+
+	list_add_tail(&ppad->list, &pipe->pads);
+
+	dev_dbg(pad->graph_obj.mdev->dev,
+		"media pipeline: added pad '%s':%u\n",
+		pad->entity->name, pad->index);
+
+	return media_pipeline_walk_push(walk, pad);
+}
+
+/* Explore the next link of the entity at the top of the stack. */
+static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
+					    struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entry = media_pipeline_walk_top(walk);
+	struct media_pad *origin;
+	struct media_link *link;
+	struct media_pad *local;
+	struct media_pad *remote;
+	bool last_link;
+	int ret;
+
+	origin = entry->pad;
+	link = list_entry(entry->links, typeof(*link), list);
+	last_link = media_pipeline_walk_pop(walk);
+
+	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (not data-link)\n");
+		return 0;
 	}
 
-	ret = fwnode_graph_parse_endpoint(fwnode, &endpoint);
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: exploring link '%s':%u -> '%s':%u\n",
+		link->source->entity->name, link->source->index,
+		link->sink->entity->name, link->sink->index);
+
+	/* Get the local pad and remote pad. */
+	if (link->source->entity == origin->entity) {
+		local = link->source;
+		remote = link->sink;
+	} else {
+		local = link->sink;
+		remote = link->source;
+	}
+
+	/*
+	 * Skip links that originate from a different pad than the incoming pad
+	 * that is not connected internally in the entity to the incoming pad.
+	 */
+	if (origin != local &&
+	    !media_entity_has_pad_interdep(origin->entity, origin->index,
+					   local->index)) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (no route)\n");
+		goto done;
+	}
+
+	/*
+	 * Add the local pad of the link to the pipeline and push it to the
+	 * stack, if not already present.
+	 */
+	ret = media_pipeline_add_pad(pipe, walk, local);
 	if (ret)
 		return ret;
 
-	ret = entity->ops->get_fwnode_pad(entity, &endpoint);
-	if (ret < 0)
+	/* Similarly, add the remote pad, but only if the link is enabled. */
+	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (disabled)\n");
+		goto done;
+	}
+
+	ret = media_pipeline_add_pad(pipe, walk, remote);
+	if (ret)
 		return ret;
 
-	if (ret >= entity->num_pads)
-		return -ENXIO;
+done:
+	/*
+	 * If we're done iterating over links, iterate over pads of the entity.
+	 * This is necessary to discover pads that are not connected with any
+	 * link. Those are dead ends from a pipeline exploration point of view,
+	 * but are still part of the pipeline and need to be added to enable
+	 * proper validation.
+	 */
+	if (!last_link)
+		return 0;
 
-	if (!(entity->pads[ret].flags & direction_flags))
-		return -ENXIO;
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: adding unconnected pads of '%s' reachable from pad %u\n",
+		origin->entity->name, origin->index);
 
-	return ret;
+	media_entity_for_each_pad(origin->entity, local) {
+		/*
+		 * Skip the origin pad (already handled), pad that have links
+		 * (already discovered through iterating over links) and pads
+		 * not internally connected.
+		 */
+		if (origin == local || local->num_links ||
+		    !media_entity_has_pad_interdep(origin->entity, origin->index,
+						   local->index))
+			continue;
+
+		ret = media_pipeline_add_pad(pipe, walk, local);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
-EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
 
-/* -----------------------------------------------------------------------------
- * Pipeline management
- */
+static void media_pipeline_cleanup(struct media_pipeline *pipe)
+{
+	while (!list_empty(&pipe->pads)) {
+		struct media_pipeline_pad *ppad;
 
-__must_check int __media_pipeline_start(struct media_entity *entity,
-					struct media_pipeline *pipe)
+		ppad = list_first_entry(&pipe->pads, typeof(*ppad), list);
+		list_del(&ppad->list);
+		kfree(ppad);
+	}
+}
+
+static int media_pipeline_populate(struct media_pipeline *pipe,
+				   struct media_pad *pad)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
-	struct media_graph *graph = &pipe->graph;
-	struct media_entity *entity_err = entity;
-	struct media_link *link;
+	struct media_pipeline_walk walk = { };
+	struct media_pipeline_pad *ppad;
 	int ret;
 
-	if (!pipe->streaming_count++) {
-		ret = media_graph_walk_init(&pipe->graph, mdev);
+	/*
+	 * Populate the media pipeline by walking the media graph, starting
+	 * from @pad.
+	 */
+	INIT_LIST_HEAD(&pipe->pads);
+	pipe->mdev = pad->graph_obj.mdev;
+
+	walk.mdev = pipe->mdev;
+	walk.stack.top = -1;
+	ret = media_pipeline_add_pad(pipe, &walk, pad);
+	if (ret)
+		goto done;
+
+	/*
+	 * Use a depth-first search algorithm: as long as the stack is not
+	 * empty, explore the next link of the top entry. The
+	 * media_pipeline_explore_next_link() function will either move to the
+	 * next link, pop the entry if fully visited, or add new entries on
+	 * top.
+	 */
+	while (!media_pipeline_walk_empty(&walk)) {
+		ret = media_pipeline_explore_next_link(pipe, &walk);
 		if (ret)
-			goto error_graph_walk_start;
+			goto done;
 	}
 
-	media_graph_walk_start(&pipe->graph, entity);
+	dev_dbg(pad->graph_obj.mdev->dev,
+		"media pipeline populated, found pads:\n");
 
-	while ((entity = media_graph_walk_next(graph))) {
-		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
-		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
+	list_for_each_entry(ppad, &pipe->pads, list)
+		dev_dbg(pad->graph_obj.mdev->dev, "- '%s':%u\n",
+			ppad->pad->entity->name, ppad->pad->index);
 
-		entity->stream_count++;
+	WARN_ON(walk.stack.top != -1);
 
-		if (entity->pipe && entity->pipe != pipe) {
-			pr_err("Pipe active for %s. Can't start for %s\n",
-				entity->name,
-				entity_err->name);
-			ret = -EBUSY;
-			goto error;
-		}
+	ret = 0;
 
-		entity->pipe = pipe;
+done:
+	media_pipeline_walk_destroy(&walk);
 
-		/* Already streaming --- no need to check. */
-		if (entity->stream_count > 1)
-			continue;
+	if (ret)
+		media_pipeline_cleanup(pipe);
 
-		if (!entity->ops || !entity->ops->link_validate)
-			continue;
+	return ret;
+}
 
-		bitmap_zero(active, entity->num_pads);
-		bitmap_fill(has_no_links, entity->num_pads);
+__must_check int __media_pipeline_start(struct media_pad *origin,
+					struct media_pipeline *pipe)
+{
+	struct media_device *mdev = origin->graph_obj.mdev;
+	struct media_pipeline_pad *err_ppad;
+	struct media_pipeline_pad *ppad;
+	int ret;
 
-		list_for_each_entry(link, &entity->links, list) {
-			struct media_pad *pad = link->sink->entity == entity
-						? link->sink : link->source;
+	lockdep_assert_held(&mdev->graph_mutex);
 
-			/* Mark that a pad is connected by a link. */
-			bitmap_clear(has_no_links, pad->index, 1);
+	/*
+	 * If the pad is already part of a pipeline, that pipeline must be the
+	 * same as the pipe given to media_pipeline_start().
+	 */
+	if (WARN_ON(origin->pipe && origin->pipe != pipe))
+		return -EINVAL;
 
-			/*
-			 * Pads that either do not need to connect or
-			 * are connected through an enabled link are
-			 * fine.
-			 */
-			if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
-			    link->flags & MEDIA_LNK_FL_ENABLED)
-				bitmap_set(active, pad->index, 1);
+	/*
+	 * If the pipeline has already been started, it is guaranteed to be
+	 * valid, so just increase the start count.
+	 */
+	if (pipe->start_count) {
+		pipe->start_count++;
+		return 0;
+	}
+
+	/*
+	 * Populate the pipeline. This populates the media_pipeline pads list
+	 * with media_pipeline_pad instances for each pad found during graph
+	 * walk.
+	 */
+	ret = media_pipeline_populate(pipe, origin);
+	if (ret)
+		return ret;
+
+	/*
+	 * Now that all the pads in the pipeline have been gathered, perform
+	 * the validation steps.
+	 */
+
+	list_for_each_entry(ppad, &pipe->pads, list) {
+		struct media_pad *pad = ppad->pad;
+		struct media_entity *entity = pad->entity;
+		bool has_enabled_link = false;
+		struct media_link *link;
+
+		dev_dbg(mdev->dev, "Validating pad '%s':%u\n", pad->entity->name,
+			pad->index);
+
+		/*
+		 * 1. Ensure that the pad doesn't already belong to a different
+		 * pipeline.
+		 */
+		if (pad->pipe) {
+			dev_dbg(mdev->dev, "Failed to start pipeline: pad '%s':%u busy\n",
+				pad->entity->name, pad->index);
+			ret = -EBUSY;
+			goto error;
+		}
+
+		/*
+		 * 2. Validate all active links whose sink is the current pad.
+		 * Validation of the source pads is performed in the context of
+		 * the connected sink pad to avoid duplicating checks.
+		 */
+		for_each_media_entity_data_link(entity, link) {
+			/* Skip links unrelated to the current pad. */
+			if (link->sink != pad && link->source != pad)
+				continue;
+
+			/* Record if the pad has links and enabled links. */
+			if (link->flags & MEDIA_LNK_FL_ENABLED)
+				has_enabled_link = true;
 
 			/*
-			 * Link validation will only take place for
-			 * sink ends of the link that are enabled.
+			 * Validate the link if it's enabled and has the
+			 * current pad as its sink.
 			 */
-			if (link->sink != pad ||
-			    !(link->flags & MEDIA_LNK_FL_ENABLED))
+			if (!(link->flags & MEDIA_LNK_FL_ENABLED))
+				continue;
+
+			if (link->sink != pad)
+				continue;
+
+			if (!entity->ops || !entity->ops->link_validate)
 				continue;
 
 			ret = entity->ops->link_validate(link);
-			if (ret < 0 && ret != -ENOIOCTLCMD) {
-				dev_dbg(entity->graph_obj.mdev->dev,
-					"link validation failed for '%s':%u -> '%s':%u, error %d\n",
+			if (ret) {
+				dev_dbg(mdev->dev,
+					"Link '%s':%u -> '%s':%u failed validation: %d\n",
 					link->source->entity->name,
 					link->source->index,
-					entity->name, link->sink->index, ret);
+					link->sink->entity->name,
+					link->sink->index, ret);
 				goto error;
 			}
-		}
 
-		/* Either no links or validated links are fine. */
-		bitmap_or(active, active, has_no_links, entity->num_pads);
+			dev_dbg(mdev->dev,
+				"Link '%s':%u -> '%s':%u is valid\n",
+				link->source->entity->name,
+				link->source->index,
+				link->sink->entity->name,
+				link->sink->index);
+		}
 
-		if (!bitmap_full(active, entity->num_pads)) {
+		/*
+		 * 3. If the pad has the MEDIA_PAD_FL_MUST_CONNECT flag set,
+		 * ensure that it has either no link or an enabled link.
+		 */
+		if ((pad->flags & MEDIA_PAD_FL_MUST_CONNECT) &&
+		    !has_enabled_link) {
+			dev_dbg(mdev->dev,
+				"Pad '%s':%u must be connected by an enabled link\n",
+				pad->entity->name, pad->index);
 			ret = -ENOLINK;
-			dev_dbg(entity->graph_obj.mdev->dev,
-				"'%s':%u must be connected by an enabled link\n",
-				entity->name,
-				(unsigned)find_first_zero_bit(
-					active, entity->num_pads));
 			goto error;
 		}
+
+		/* Validation passed, store the pipe pointer in the pad. */
+		pad->pipe = pipe;
 	}
 
+	pipe->start_count++;
+
 	return 0;
 
 error:
@@ -504,49 +900,37 @@ error:
 	 * Link validation on graph failed. We revert what we did and
 	 * return the error.
 	 */
-	media_graph_walk_start(graph, entity_err);
-
-	while ((entity_err = media_graph_walk_next(graph))) {
-		/* Sanity check for negative stream_count */
-		if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {
-			entity_err->stream_count--;
-			if (entity_err->stream_count == 0)
-				entity_err->pipe = NULL;
-		}
 
-		/*
-		 * We haven't increased stream_count further than this
-		 * so we quit here.
-		 */
-		if (entity_err == entity)
+	list_for_each_entry(err_ppad, &pipe->pads, list) {
+		if (err_ppad == ppad)
 			break;
+
+		err_ppad->pad->pipe = NULL;
 	}
 
-error_graph_walk_start:
-	if (!--pipe->streaming_count)
-		media_graph_walk_cleanup(graph);
+	media_pipeline_cleanup(pipe);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__media_pipeline_start);
 
-__must_check int media_pipeline_start(struct media_entity *entity,
+__must_check int media_pipeline_start(struct media_pad *origin,
 				      struct media_pipeline *pipe)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_device *mdev = origin->graph_obj.mdev;
 	int ret;
 
 	mutex_lock(&mdev->graph_mutex);
-	ret = __media_pipeline_start(entity, pipe);
+	ret = __media_pipeline_start(origin, pipe);
 	mutex_unlock(&mdev->graph_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(media_pipeline_start);
 
-void __media_pipeline_stop(struct media_entity *entity)
+void __media_pipeline_stop(struct media_pad *pad)
 {
-	struct media_graph *graph = &entity->pipe->graph;
-	struct media_pipeline *pipe = entity->pipe;
+	struct media_pipeline *pipe = pad->pipe;
+	struct media_pipeline_pad *ppad;
 
 	/*
 	 * If the following check fails, the driver has performed an
@@ -555,33 +939,120 @@ void __media_pipeline_stop(struct media_entity *entity)
 	if (WARN_ON(!pipe))
 		return;
 
-	media_graph_walk_start(graph, entity);
+	if (--pipe->start_count)
+		return;
 
-	while ((entity = media_graph_walk_next(graph))) {
-		/* Sanity check for negative stream_count */
-		if (!WARN_ON_ONCE(entity->stream_count <= 0)) {
-			entity->stream_count--;
-			if (entity->stream_count == 0)
-				entity->pipe = NULL;
-		}
-	}
+	list_for_each_entry(ppad, &pipe->pads, list)
+		ppad->pad->pipe = NULL;
 
-	if (!--pipe->streaming_count)
-		media_graph_walk_cleanup(graph);
+	media_pipeline_cleanup(pipe);
 
+	if (pipe->allocated)
+		kfree(pipe);
 }
 EXPORT_SYMBOL_GPL(__media_pipeline_stop);
 
-void media_pipeline_stop(struct media_entity *entity)
+void media_pipeline_stop(struct media_pad *pad)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_device *mdev = pad->graph_obj.mdev;
 
 	mutex_lock(&mdev->graph_mutex);
-	__media_pipeline_stop(entity);
+	__media_pipeline_stop(pad);
 	mutex_unlock(&mdev->graph_mutex);
 }
 EXPORT_SYMBOL_GPL(media_pipeline_stop);
 
+__must_check int media_pipeline_alloc_start(struct media_pad *pad)
+{
+	struct media_device *mdev = pad->graph_obj.mdev;
+	struct media_pipeline *new_pipe = NULL;
+	struct media_pipeline *pipe;
+	int ret;
+
+	mutex_lock(&mdev->graph_mutex);
+
+	/*
+	 * Is the pad already part of a pipeline? If not, we need to allocate
+	 * a pipe.
+	 */
+	pipe = media_pad_pipeline(pad);
+	if (!pipe) {
+		new_pipe = kzalloc(sizeof(*new_pipe), GFP_KERNEL);
+		if (!new_pipe) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		pipe = new_pipe;
+		pipe->allocated = true;
+	}
+
+	ret = __media_pipeline_start(pad, pipe);
+	if (ret)
+		kfree(new_pipe);
+
+out:
+	mutex_unlock(&mdev->graph_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_pipeline_alloc_start);
+
+struct media_pad *
+__media_pipeline_pad_iter_next(struct media_pipeline *pipe,
+			       struct media_pipeline_pad_iter *iter,
+			       struct media_pad *pad)
+{
+	if (!pad)
+		iter->cursor = pipe->pads.next;
+
+	if (iter->cursor == &pipe->pads)
+		return NULL;
+
+	pad = list_entry(iter->cursor, struct media_pipeline_pad, list)->pad;
+	iter->cursor = iter->cursor->next;
+
+	return pad;
+}
+EXPORT_SYMBOL_GPL(__media_pipeline_pad_iter_next);
+
+int media_pipeline_entity_iter_init(struct media_pipeline *pipe,
+				    struct media_pipeline_entity_iter *iter)
+{
+	return media_entity_enum_init(&iter->ent_enum, pipe->mdev);
+}
+EXPORT_SYMBOL_GPL(media_pipeline_entity_iter_init);
+
+void media_pipeline_entity_iter_cleanup(struct media_pipeline_entity_iter *iter)
+{
+	media_entity_enum_cleanup(&iter->ent_enum);
+}
+EXPORT_SYMBOL_GPL(media_pipeline_entity_iter_cleanup);
+
+struct media_entity *
+__media_pipeline_entity_iter_next(struct media_pipeline *pipe,
+				  struct media_pipeline_entity_iter *iter,
+				  struct media_entity *entity)
+{
+	if (!entity)
+		iter->cursor = pipe->pads.next;
+
+	while (iter->cursor != &pipe->pads) {
+		struct media_pipeline_pad *ppad;
+		struct media_entity *entity;
+
+		ppad = list_entry(iter->cursor, struct media_pipeline_pad, list);
+		entity = ppad->pad->entity;
+		iter->cursor = iter->cursor->next;
+
+		if (!media_entity_enum_test_and_set(&iter->ent_enum, entity))
+			return entity;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__media_pipeline_entity_iter_next);
+
 /* -----------------------------------------------------------------------------
  * Links management
  */
@@ -605,50 +1076,51 @@ static void __media_entity_remove_link(struct media_entity *entity,
 	struct media_link *rlink, *tmp;
 	struct media_entity *remote;
 
-	if (link->source->entity == entity)
-		remote = link->sink->entity;
-	else
-		remote = link->source->entity;
-
-	list_for_each_entry_safe(rlink, tmp, &remote->links, list) {
-		if (rlink != link->reverse)
-			continue;
+	/* Remove the reverse links for a data link. */
+	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) == MEDIA_LNK_FL_DATA_LINK) {
+		link->source->num_links--;
+		link->sink->num_links--;
 
 		if (link->source->entity == entity)
-			remote->num_backlinks--;
+			remote = link->sink->entity;
+		else
+			remote = link->source->entity;
 
-		/* Remove the remote link */
-		list_del(&rlink->list);
-		media_gobj_destroy(&rlink->graph_obj);
-		kfree(rlink);
+		list_for_each_entry_safe(rlink, tmp, &remote->links, list) {
+			if (rlink != link->reverse)
+				continue;
 
-		if (--remote->num_links == 0)
-			break;
+			if (link->source->entity == entity)
+				remote->num_backlinks--;
+
+			/* Remove the remote link */
+			list_del(&rlink->list);
+			media_gobj_destroy(&rlink->graph_obj);
+			kfree(rlink);
+
+			if (--remote->num_links == 0)
+				break;
+		}
 	}
+
 	list_del(&link->list);
 	media_gobj_destroy(&link->graph_obj);
 	kfree(link);
 }
 
-int media_get_pad_index(struct media_entity *entity, bool is_sink,
+int media_get_pad_index(struct media_entity *entity, u32 pad_type,
 			enum media_pad_signal_type sig_type)
 {
-	int i;
-	bool pad_is_sink;
+	unsigned int i;
 
 	if (!entity)
 		return -EINVAL;
 
 	for (i = 0; i < entity->num_pads; i++) {
-		if (entity->pads[i].flags & MEDIA_PAD_FL_SINK)
-			pad_is_sink = true;
-		else if (entity->pads[i].flags & MEDIA_PAD_FL_SOURCE)
-			pad_is_sink = false;
-		else
-			continue;	/* This is an error! */
-
-		if (pad_is_sink != is_sink)
+		if ((entity->pads[i].flags &
+		     (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE)) != pad_type)
 			continue;
+
 		if (entity->pads[i].sig_type == sig_type)
 			return i;
 	}
@@ -663,6 +1135,11 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
 	struct media_link *link;
 	struct media_link *backlink;
 
+	if (flags & MEDIA_LNK_FL_LINK_TYPE)
+		return -EINVAL;
+
+	flags |= MEDIA_LNK_FL_DATA_LINK;
+
 	if (WARN_ON(!source || !sink) ||
 	    WARN_ON(source_pad >= source->num_pads) ||
 	    WARN_ON(sink_pad >= sink->num_pads))
@@ -678,7 +1155,7 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
 
 	link->source = &source->pads[source_pad];
 	link->sink = &sink->pads[sink_pad];
-	link->flags = flags & ~MEDIA_LNK_FL_INTERFACE_LINK;
+	link->flags = flags;
 
 	/* Initialize graph object embedded at the new link */
 	media_gobj_create(source->graph_obj.mdev, MEDIA_GRAPH_LINK,
@@ -709,6 +1186,9 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
 	sink->num_links++;
 	source->num_links++;
 
+	link->source->num_links++;
+	link->sink->num_links++;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(media_create_pad_link);
@@ -832,7 +1312,7 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
 {
 	const u32 mask = MEDIA_LNK_FL_ENABLED;
 	struct media_device *mdev;
-	struct media_entity *source, *sink;
+	struct media_pad *source, *sink;
 	int ret = -EBUSY;
 
 	if (link == NULL)
@@ -848,11 +1328,11 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
 	if (link->flags == flags)
 		return 0;
 
-	source = link->source->entity;
-	sink = link->sink->entity;
+	source = link->source;
+	sink = link->sink;
 
 	if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
-	    (source->stream_count || sink->stream_count))
+	    (media_pad_is_streaming(source) || media_pad_is_streaming(sink)))
 		return -EBUSY;
 
 	mdev = source->graph_obj.mdev;
@@ -891,7 +1371,7 @@ media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 {
 	struct media_link *link;
 
-	list_for_each_entry(link, &source->entity->links, list) {
+	for_each_media_entity_data_link(source->entity, link) {
 		if (link->source->entity == source->entity &&
 		    link->source->index == source->index &&
 		    link->sink->entity == sink->entity &&
@@ -903,11 +1383,11 @@ media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 }
 EXPORT_SYMBOL_GPL(media_entity_find_link);
 
-struct media_pad *media_entity_remote_pad(const struct media_pad *pad)
+struct media_pad *media_pad_remote_pad_first(const struct media_pad *pad)
 {
 	struct media_link *link;
 
-	list_for_each_entry(link, &pad->entity->links, list) {
+	for_each_media_entity_data_link(pad->entity, link) {
 		if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 			continue;
 
@@ -921,7 +1401,131 @@ struct media_pad *media_entity_remote_pad(const struct media_pad *pad)
 	return NULL;
 
 }
-EXPORT_SYMBOL_GPL(media_entity_remote_pad);
+EXPORT_SYMBOL_GPL(media_pad_remote_pad_first);
+
+struct media_pad *
+media_entity_remote_pad_unique(const struct media_entity *entity,
+			       unsigned int type)
+{
+	struct media_pad *pad = NULL;
+	struct media_link *link;
+
+	list_for_each_entry(link, &entity->links, list) {
+		struct media_pad *local_pad;
+		struct media_pad *remote_pad;
+
+		if (((link->flags & MEDIA_LNK_FL_LINK_TYPE) !=
+		     MEDIA_LNK_FL_DATA_LINK) ||
+		    !(link->flags & MEDIA_LNK_FL_ENABLED))
+			continue;
+
+		if (type == MEDIA_PAD_FL_SOURCE) {
+			local_pad = link->sink;
+			remote_pad = link->source;
+		} else {
+			local_pad = link->source;
+			remote_pad = link->sink;
+		}
+
+		if (local_pad->entity == entity) {
+			if (pad)
+				return ERR_PTR(-ENOTUNIQ);
+
+			pad = remote_pad;
+		}
+	}
+
+	if (!pad)
+		return ERR_PTR(-ENOLINK);
+
+	return pad;
+}
+EXPORT_SYMBOL_GPL(media_entity_remote_pad_unique);
+
+struct media_pad *media_pad_remote_pad_unique(const struct media_pad *pad)
+{
+	struct media_pad *found_pad = NULL;
+	struct media_link *link;
+
+	list_for_each_entry(link, &pad->entity->links, list) {
+		struct media_pad *remote_pad;
+
+		if (!(link->flags & MEDIA_LNK_FL_ENABLED))
+			continue;
+
+		if (link->sink == pad)
+			remote_pad = link->source;
+		else if (link->source == pad)
+			remote_pad = link->sink;
+		else
+			continue;
+
+		if (found_pad)
+			return ERR_PTR(-ENOTUNIQ);
+
+		found_pad = remote_pad;
+	}
+
+	if (!found_pad)
+		return ERR_PTR(-ENOLINK);
+
+	return found_pad;
+}
+EXPORT_SYMBOL_GPL(media_pad_remote_pad_unique);
+
+int media_entity_get_fwnode_pad(struct media_entity *entity,
+				const struct fwnode_handle *fwnode,
+				unsigned long direction_flags)
+{
+	struct fwnode_endpoint endpoint;
+	unsigned int i;
+	int ret;
+
+	if (!entity->ops || !entity->ops->get_fwnode_pad) {
+		for (i = 0; i < entity->num_pads; i++) {
+			if (entity->pads[i].flags & direction_flags)
+				return i;
+		}
+
+		return -ENXIO;
+	}
+
+	ret = fwnode_graph_parse_endpoint(fwnode, &endpoint);
+	if (ret)
+		return ret;
+
+	ret = entity->ops->get_fwnode_pad(entity, &endpoint);
+	if (ret < 0)
+		return ret;
+
+	if (ret >= entity->num_pads)
+		return -ENXIO;
+
+	if (!(entity->pads[ret].flags & direction_flags))
+		return -ENXIO;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
+
+struct media_pipeline *media_entity_pipeline(struct media_entity *entity)
+{
+	struct media_pad *pad;
+
+	media_entity_for_each_pad(entity, pad) {
+		if (pad->pipe)
+			return pad->pipe;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline);
+
+struct media_pipeline *media_pad_pipeline(struct media_pad *pad)
+{
+	return pad->pipe;
+}
+EXPORT_SYMBOL_GPL(media_pad_pipeline);
 
 static void media_interface_init(struct media_device *mdev,
 				 struct media_interface *intf,
@@ -1032,3 +1636,40 @@ void media_remove_intf_links(struct media_interface *intf)
 	mutex_unlock(&mdev->graph_mutex);
 }
 EXPORT_SYMBOL_GPL(media_remove_intf_links);
+
+struct media_link *media_create_ancillary_link(struct media_entity *primary,
+					       struct media_entity *ancillary)
+{
+	struct media_link *link;
+
+	link = media_add_link(&primary->links);
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+
+	link->gobj0 = &primary->graph_obj;
+	link->gobj1 = &ancillary->graph_obj;
+	link->flags = MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED |
+		      MEDIA_LNK_FL_ANCILLARY_LINK;
+
+	/* Initialize graph object embedded in the new link */
+	media_gobj_create(primary->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			  &link->graph_obj);
+
+	return link;
+}
+EXPORT_SYMBOL_GPL(media_create_ancillary_link);
+
+struct media_link *__media_entity_next_link(struct media_entity *entity,
+					    struct media_link *link,
+					    unsigned long link_type)
+{
+	link = link ? list_next_entry(link, list)
+		    : list_first_entry(&entity->links, typeof(*link), list);
+
+	list_for_each_entry_from(link, &entity->links, list)
+		if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) == link_type)
+			return link;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__media_entity_next_link);