[libcamera-devel] [PATCH v2 2/5] libcamera: pipeline: simple: Document the pipeline traversal algorithm

Laurent Pinchart laurent.pinchart at ideasonboard.com
Sun Jun 12 17:23:08 CEST 2022


Add a section to the documentation at the top of the file to describe in
a bit more details how the media graph is traversed.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/pipeline/simple/simple.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index efb28ccd97e8..b09368aee20b 100644
--- a/src/libcamera/pipeline/simple/simple.cpp
+++ b/src/libcamera/pipeline/simple/simple.cpp
@@ -95,6 +95,21 @@ LOG_DEFINE_CATEGORY(SimplePipeline)
  * valid pipeline configurations are found, a Camera is registered for the
  * SimpleCameraData instance.
  *
+ * Pipeline Traversal
+ * ------------------
+ *
+ * During the breadth-first search, the pipeline is traversed from entity to
+ * entity, by following media graph links from source to sink, starting at the
+ * camera sensor. When reaching an entity (on its sink side), all its source
+ * pads are considered to continue the graph traversal.
+ *
+ * The shortest path between the camera sensor and a video node is stored in
+ * SimpleCameraData::entities_ as a list of SimpleCameraData::Entity structures,
+ * ordered along the data path from the camera sensor to the video node. The
+ * Entity structure stores a pointer to the MediaEntity, as well as information
+ * about how it is connected in that particular path for later usage when
+ * configuring the pipeline.
+ *
  * Pipeline Configuration
  * ----------------------
  *
-- 
Regards,

Laurent Pinchart



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