libcamera: ipu3: cio2: Hide buffer allocation and freeing from users

The allocation and freeing of buffers for the CIO2 is handled in the
IPU3 pipeline handlers start() and stop() functions. These functions
also call CIO2Device start() and stop() at the appropriate times so
move the CIO2 buffer allocation/freeing inside the CIO2Device and reduce
the complexity of the exposed interface.

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

src/libcamera/pipeline/ipu3/cio2.cpp

@@ -207,44 +207,12 @@ CIO2Device::generateConfiguration(Size size) const
 	return cfg;
 }
 
-/**
- * \brief Allocate frame buffers for the CIO2 output
- *
- * Allocate frame buffers in the CIO2 video device to be used to capture frames
- * from the CIO2 output. The buffers are stored in the CIO2Device::buffers_
- * vector.
- *
- * \return Number of buffers allocated or negative error code
- */
-int CIO2Device::allocateBuffers()
-{
-	int ret = output_->allocateBuffers(CIO2_BUFFER_COUNT, &buffers_);
-	if (ret < 0)
-		return ret;
-
-	for (std::unique_ptr<FrameBuffer> &buffer : buffers_)
-		availableBuffers_.push(buffer.get());
-
-	return ret;
-}
-
 int CIO2Device::exportBuffers(unsigned int count,
 			      std::vector<std::unique_ptr<FrameBuffer>> *buffers)
 {
 	return output_->exportBuffers(count, buffers);
 }
 
-void CIO2Device::freeBuffers()
-{
-	/* The default std::queue constructor is explicit with gcc 5 and 6. */
-	availableBuffers_ = std::queue<FrameBuffer *>{};
-
-	buffers_.clear();
-
-	if (output_->releaseBuffers())
-		LOG(IPU3, Error) << "Failed to release CIO2 buffers";
-}
-
 FrameBuffer *CIO2Device::getBuffer()
 {
 	if (availableBuffers_.empty()) {
@@ -266,12 +234,27 @@ void CIO2Device::putBuffer(FrameBuffer *buffer)
 
 int CIO2Device::start()
 {
-	return output_->streamOn();
+	int ret = output_->allocateBuffers(CIO2_BUFFER_COUNT, &buffers_);
+	if (ret < 0)
+		return ret;
+
+	for (std::unique_ptr<FrameBuffer> &buffer : buffers_)
+		availableBuffers_.push(buffer.get());
+
+	ret = output_->streamOn();
+	if (ret)
+		freeBuffers();
+
+	return ret;
 }
 
 int CIO2Device::stop()
 {
-	return output_->streamOff();
+	int ret = output_->streamOff();
+
+	freeBuffers();
+
+	return ret;
 }
 
 int CIO2Device::queueBuffer(FrameBuffer *buffer)
@@ -279,6 +262,17 @@ int CIO2Device::queueBuffer(FrameBuffer *buffer)
 	return output_->queueBuffer(buffer);
 }
 
+void CIO2Device::freeBuffers()
+{
+	/* The default std::queue constructor is explicit with gcc 5 and 6. */
+	availableBuffers_ = std::queue<FrameBuffer *>{};
+
+	buffers_.clear();
+
+	if (output_->releaseBuffers())
+		LOG(IPU3, Error) << "Failed to release CIO2 buffers";
+}
+
 void CIO2Device::cio2BufferReady(FrameBuffer *buffer)
 {
 	bufferReady.emit(buffer);

src/libcamera/pipeline/ipu3/cio2.h

@@ -37,10 +37,8 @@ public:
 
 	StreamConfiguration generateConfiguration(Size size) const;
 
-	int allocateBuffers();
 	int exportBuffers(unsigned int count,
 			  std::vector<std::unique_ptr<FrameBuffer>> *buffers);
-	void freeBuffers();
 
 	FrameBuffer *getBuffer();
 	void putBuffer(FrameBuffer *buffer);
@@ -54,6 +52,8 @@ public:
 	Signal<FrameBuffer *> bufferReady;
 
 private:
+	void freeBuffers();
+
 	void cio2BufferReady(FrameBuffer *buffer);
 
 	CameraSensor *sensor_;

src/libcamera/pipeline/ipu3/ipu3.cpp

@@ -658,15 +658,10 @@ int PipelineHandlerIPU3::exportFrameBuffers(Camera *camera, Stream *stream,
 int PipelineHandlerIPU3::allocateBuffers(Camera *camera)
 {
 	IPU3CameraData *data = cameraData(camera);
-	CIO2Device *cio2 = &data->cio2_;
 	ImgUDevice *imgu = data->imgu_;
 	unsigned int bufferCount;
 	int ret;
 
-	ret = cio2->allocateBuffers();
-	if (ret < 0)
-		return ret;
-
 	bufferCount = std::max({
 		data->outStream_.configuration().bufferCount,
 		data->vfStream_.configuration().bufferCount,
@@ -674,10 +669,8 @@ int PipelineHandlerIPU3::allocateBuffers(Camera *camera)
 	});
 
 	ret = imgu->allocateBuffers(data, bufferCount);
-	if (ret < 0) {
+	if (ret < 0)
-		cio2->freeBuffers();
 		return ret;
-	}
 
 	return 0;
 }
@@ -686,7 +679,6 @@ int PipelineHandlerIPU3::freeBuffers(Camera *camera)
 {
 	IPU3CameraData *data = cameraData(camera);
 
-	data->cio2_.freeBuffers();
 	data->imgu_->freeBuffers(data);
 
 	return 0;
@@ -731,10 +723,10 @@ error:
 void PipelineHandlerIPU3::stop(Camera *camera)
 {
 	IPU3CameraData *data = cameraData(camera);
-	int ret;
+	int ret = 0;
 
-	ret = data->cio2_.stop();
 	ret |= data->imgu_->stop();
+	ret |= data->cio2_.stop();
 	if (ret)
 		LOG(IPU3, Warning) << "Failed to stop camera "
 				   << camera->name();