libcamera: Handle request completion explicitly in pipeline handlers

Request complete by themselves when all the buffers they contain have
completed, connecting the buffer's completed signal to be notified of
buffer completion. While this works for now, it prevents pipelines from
delaying request completion until all metadata is available, and makes
it impossible to ensure that requests complete in the order they are
queued.

To fix this, make request completion handling explicit in pipeline
handlers. The base PipelineHandler class is extended with
implementations of the queueRequest() and stop() methods and gets new
completeBuffer() and completeRequest() methods to help pipeline handlers
tracking requests and buffers.

The three existing pipeline handlers connect the bufferReady signal of
their capture video node to a slot of their respective camera data
instance, where they use the PipelineHandler helpers to notify buffer
and request completion. Request completion is handled synchronously with
buffer completion as the pipeline handlers don't need to support more
advanced use cases, but this paves the road for future work.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/pipeline/ipu3/ipu3.cpp

@@ -63,6 +63,8 @@ private:
 			delete sensor_;
 		}
 
+		void bufferReady(Buffer *buffer);
+
 		V4L2Device *cio2_;
 		V4L2Subdevice *csi2_;
 		V4L2Subdevice *sensor_;
@@ -236,6 +238,8 @@ void PipelineHandlerIPU3::stop(Camera *camera)
 
 	if (data->cio2_->streamOff())
 		LOG(IPU3, Info) << "Failed to stop camera " << camera->name();
+
+	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerIPU3::queueRequest(Camera *camera, Request *request)
@@ -250,7 +254,11 @@ int PipelineHandlerIPU3::queueRequest(Camera *camera, Request *request)
 		return -ENOENT;
 	}
 
-	data->cio2_->queueBuffer(buffer);
+	int ret = data->cio2_->queueBuffer(buffer);
+	if (ret < 0)
+		return ret;
+
+	PipelineHandler::queueRequest(camera, request);
 
 	return 0;
 }
@@ -396,6 +404,8 @@ void PipelineHandlerIPU3::registerCameras()
 		if (ret)
 			continue;
 
+		data->cio2_->bufferReady.connect(data.get(), &IPU3CameraData::bufferReady);
+
 		data->sensor_ = new V4L2Subdevice(sensor);
 		ret = data->sensor_->open();
 		if (ret)
@@ -417,6 +427,14 @@ void PipelineHandlerIPU3::registerCameras()
 	}
 }
 
+void PipelineHandlerIPU3::IPU3CameraData::bufferReady(Buffer *buffer)
+{
+	Request *request = queuedRequests_.front();
+
+	pipe_->completeBuffer(camera_, request, buffer);
+	pipe_->completeRequest(camera_, request);
+}
+
 REGISTER_PIPELINE_HANDLER(PipelineHandlerIPU3);
 
 } /* namespace libcamera */

src/libcamera/pipeline/uvcvideo.cpp

@@ -56,6 +56,8 @@ private:
 			delete video_;
 		}
 
+		void bufferReady(Buffer *buffer);
+
 		V4L2Device *video_;
 		Stream stream_;
 	};
@@ -153,6 +155,7 @@ void PipelineHandlerUVC::stop(Camera *camera)
 {
 	UVCCameraData *data = cameraData(camera);
 	data->video_->streamOff();
+	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerUVC::queueRequest(Camera *camera, Request *request)
@@ -166,7 +169,11 @@ int PipelineHandlerUVC::queueRequest(Camera *camera, Request *request)
 		return -ENOENT;
 	}
 
-	data->video_->queueBuffer(buffer);
+	int ret = data->video_->queueBuffer(buffer);
+	if (ret < 0)
+		return ret;
+
+	PipelineHandler::queueRequest(camera, request);
 
 	return 0;
 }
@@ -199,6 +206,8 @@ bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 	if (data->video_->open())
 		return false;
 
+	data->video_->bufferReady.connect(data.get(), &UVCCameraData::bufferReady);
+
 	/* Create and register the camera. */
 	std::set<Stream *> streams{ &data->stream_ };
 	std::shared_ptr<Camera> camera = Camera::create(this, media_->model(), streams);
@@ -210,6 +219,14 @@ bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 	return true;
 }
 
+void PipelineHandlerUVC::UVCCameraData::bufferReady(Buffer *buffer)
+{
+	Request *request = queuedRequests_.front();
+
+	pipe_->completeBuffer(camera_, request, buffer);
+	pipe_->completeRequest(camera_, request);
+}
+
 REGISTER_PIPELINE_HANDLER(PipelineHandlerUVC);
 
 } /* namespace libcamera */

src/libcamera/pipeline/vimc.cpp

@@ -56,6 +56,8 @@ private:
 			delete video_;
 		}
 
+		void bufferReady(Buffer *buffer);
+
 		V4L2Device *video_;
 		Stream stream_;
 	};
@@ -153,6 +155,7 @@ void PipelineHandlerVimc::stop(Camera *camera)
 {
 	VimcCameraData *data = cameraData(camera);
 	data->video_->streamOff();
+	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerVimc::queueRequest(Camera *camera, Request *request)
@@ -166,7 +169,11 @@ int PipelineHandlerVimc::queueRequest(Camera *camera, Request *request)
 		return -ENOENT;
 	}
 
-	data->video_->queueBuffer(buffer);
+	int ret = data->video_->queueBuffer(buffer);
+	if (ret < 0)
+		return ret;
+
+	PipelineHandler::queueRequest(camera, request);
 
 	return 0;
 }
@@ -198,6 +205,8 @@ bool PipelineHandlerVimc::match(DeviceEnumerator *enumerator)
 	if (data->video_->open())
 		return false;
 
+	data->video_->bufferReady.connect(data.get(), &VimcCameraData::bufferReady);
+
 	/* Create and register the camera. */
 	std::set<Stream *> streams{ &data->stream_ };
 	std::shared_ptr<Camera> camera = Camera::create(this, "VIMC Sensor B",
@@ -207,6 +216,14 @@ bool PipelineHandlerVimc::match(DeviceEnumerator *enumerator)
 	return true;
 }
 
+void PipelineHandlerVimc::VimcCameraData::bufferReady(Buffer *buffer)
+{
+	Request *request = queuedRequests_.front();
+
+	pipe_->completeBuffer(camera_, request, buffer);
+	pipe_->completeRequest(camera_, request);
+}
+
 REGISTER_PIPELINE_HANDLER(PipelineHandlerVimc);
 
 } /* namespace libcamera */