[libcamera-devel] [PATCH v4 1/6] libcamera: camera: Assert pipelines complete all requests

[Kieran Bingham]

When the camera manager calls stop on a pipeline, it is expected that
the pipeline handler guarantees all requests are returned back to the
application before the camera has stopped.

Ensure that this guarantee is met by providing an accessor on the
pipeline handler to validate that all pending requests are removed.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 include/libcamera/internal/pipeline_handler.h |  1 +
 src/libcamera/camera.cpp                      |  2 ++
 src/libcamera/pipeline_handler.cpp            | 15 +++++++++++++++
 3 files changed, 18 insertions(+)

diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
index c6454db6b2c4..27d45d8ffc20 100644
--- a/include/libcamera/internal/pipeline_handler.h
+++ b/include/libcamera/internal/pipeline_handler.h
@@ -80,6 +80,7 @@ public:
 
 	virtual int start(Camera *camera, const ControlList *controls) = 0;
 	virtual void stop(Camera *camera) = 0;
+	bool active(const Camera *camera) const;
 
 	void queueRequest(Request *request);
 
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 763f3b9926fd..c3fc3dd91bd6 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -1084,6 +1084,8 @@ int Camera::stop()
 	d->pipe_->invokeMethod(&PipelineHandler::stop, ConnectionTypeBlocking,
 			       this);
 
+	ASSERT(!d->pipe_->active(this));
+
 	d->setState(Private::CameraConfigured);
 
 	return 0;
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 3b3150bdbbf7..8629e3578f02 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -368,6 +368,21 @@ const ControlList &PipelineHandler::properties(const Camera *camera) const
  * \context This function is called from the CameraManager thread.
  */
 
+/**
+ * \brief Determine if the camera has any requests pending
+ * \param[in] camera The camera to check
+ *
+ * This method determines if there are any requests queued to the pipeline
+ * awaiting processing.
+ *
+ * \return True if there are pending requests, or false otherwise
+ */
+bool PipelineHandler::active(const Camera *camera) const
+{
+	const CameraData *data = cameraData(camera);
+	return !data->queuedRequests_.empty();
+}
+
 /**
  * \fn PipelineHandler::queueRequest()
  * \brief Queue a request
-- 
2.25.1