1 files changed, 60 insertions, 4 deletions

diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index 239f77ff..e8957b77 100644
--- a/src/libcamera/pipeline/simple/simple.cpp
+++ b/src/libcamera/pipeline/simple/simple.cpp
@@ -236,6 +236,8 @@ public:
 	std::queue<std::map<unsigned int, FrameBuffer *>> converterQueue_;
 
 private:
+	static std::vector<const MediaPad *> routedSourcePads(MediaPad *sink);
+
 	void converterInputDone(FrameBuffer *buffer);
 	void converterOutputDone(FrameBuffer *buffer);
 };
@@ -360,12 +362,29 @@ SimpleCameraData::SimpleCameraData(SimplePipelineHandler *pipe,
 			break;
 		}
 
-		/* The actual breadth-first search algorithm. */
 		visited.insert(entity);
-		for (MediaPad *pad : entity->pads()) {
-			if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
-				continue;
 
+		/*
+		 * Add direct downstream entities to the search queue. If the
+		 * current entity supports the subdev internal routing API,
+		 * restrict the search to downstream entities reachable through
+		 * active routes.
+		 */
+
+		std::vector<const MediaPad *> pads;
+
+		if (sinkPad)
+			pads = routedSourcePads(sinkPad);
+
+		if (pads.empty()) {
+			for (const MediaPad *pad : entity->pads()) {
+				if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
+					continue;
+				pads.push_back(pad);
+			}
+		}
+
+		for (const MediaPad *pad : pads) {
 			for (MediaLink *link : pad->links()) {
 				MediaEntity *next = link->sink()->entity();
 				if (visited.find(next) == visited.end()) {
@@ -728,6 +747,43 @@ void SimpleCameraData::converterOutputDone(FrameBuffer *buffer)
 		pipe->completeRequest(request);
 }
 
+/* Retrieve all source pads connected to a sink pad through active routes. */
+std::vector<const MediaPad *> SimpleCameraData::routedSourcePads(MediaPad *sink)
+{
+	MediaEntity *entity = sink->entity();
+	std::unique_ptr<V4L2Subdevice> subdev =
+		std::make_unique<V4L2Subdevice>(entity);
+
+	int ret = subdev->open();
+	if (ret < 0)
+		return {};
+
+	std::vector<struct v4l2_subdev_route> routes;
+	ret = subdev->getRouting(&routes);
+	if (ret < 0)
+		return {};
+
+	std::vector<const MediaPad *> pads;
+
+	for (const struct v4l2_subdev_route &route : routes) {
+		if (sink->index() != route.sink_pad ||
+		    !(route.flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
+			continue;
+
+		const MediaPad *pad = entity->getPadByIndex(route.source_pad);
+		if (!pad) {
+			LOG(SimplePipeline, Warning)
+				<< "Entity " << entity->name()
+				<< " has invalid route source pad "
+				<< route.source_pad;
+		}
+
+		pads.push_back(pad);
+	}
+
+	return pads;
+}
+
 /* -----------------------------------------------------------------------------
  * Camera Configuration
  */