libcamera: pipeline: simple: Add sink and source pads to entity data

Record the sink and source pads through which an entity is traversed in
the list of entities stored in the camera data. This prepares for
implementing mutually exclusive access to entities between cameras.

The debug message that displays detected pipelines now prints pads to
describe the pipeline more precisely:

[0:00:35.901275750] [260] DEBUG SimplePipeline simple.cpp:404 Found pipeline: [imx290 2-001a|0] -> [0|csis-32e40000.csi|1] -> [0|mxc_isi.0|1] -> [0|mxc_isi.0.capture]

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>

1 files changed, 32 insertions, 6 deletions

diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index 8ff95472..32bfd45f 100644
--- a/src/libcamera/pipeline/simple/simple.cpp
+++ b/src/libcamera/pipeline/simple/simple.cpp
@@ -168,7 +168,22 @@ public:
 	}
 
 	struct Entity {
+		/* The media entity, always valid. */
 		MediaEntity *entity;
+		/*
+		 * The local sink pad connected to the upstream entity, null for
+		 * the camera sensor at the beginning of the pipeline.
+		 */
+		const MediaPad *sink;
+		/*
+		 * The local source pad connected to the downstream entity, null
+		 * for the video node at the end of the pipeline.
+		 */
+		const MediaPad *source;
+		/*
+		 * The link to the downstream entity, null for the video node at
+		 * the end of the pipeline.
+		 */
 		MediaLink *link;
 	};
 
@@ -289,16 +304,18 @@ SimpleCameraData::SimpleCameraData(SimplePipelineHandler *pipe,
 	 * encoders and image converters, and will end in a CSI capture device.
 	 */
 	std::unordered_set<MediaEntity *> visited;
-	std::queue<MediaEntity *> queue;
+	std::queue<std::tuple<MediaEntity *, MediaPad *>> queue;
 
 	/* Remember at each entity where we came from. */
 	std::unordered_map<MediaEntity *, Entity> parents;
 	MediaEntity *entity = nullptr;
 
-	queue.push(sensor);
+	queue.push({ sensor, nullptr });
 
 	while (!queue.empty()) {
-		entity = queue.front();
+		MediaPad *sinkPad;
+
+		std::tie(entity, sinkPad) = queue.front();
 		queue.pop();
 
 		/* Found the capture device. */
@@ -318,8 +335,8 @@ SimpleCameraData::SimpleCameraData(SimplePipelineHandler *pipe,
 			for (MediaLink *link : pad->links()) {
 				MediaEntity *next = link->sink()->entity();
 				if (visited.find(next) == visited.end()) {
-					queue.push(next);
-					parents.insert({ next, { entity, link } });
+					queue.push({ next, link->sink() });
+					parents.insert({ next, { entity, sinkPad, pad, link } });
 				}
 			}
 		}
@@ -350,7 +367,16 @@ SimpleCameraData::SimpleCameraData(SimplePipelineHandler *pipe,
 	LOG(SimplePipeline, Debug)
 		<< "Found pipeline: "
 		<< utils::join(entities_, " -> ",
-			       [](const Entity &e) { return e.entity->name(); });
+			       [](const Entity &e) {
+				       std::string s = "[";
+				       if (e.sink)
+					       s += std::to_string(e.sink->index()) + "|";
+				       s += e.entity->name();
+				       if (e.source)
+					       s += "|" + std::to_string(e.source->index());
+				       s += "]";
+				       return s;
+			       });
 }
 
 SimplePipelineHandler *SimpleCameraData::pipe()