diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index 4bfe45aaf78e34ab..fab6d3ee1f3e04d7 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -14,10 +14,12 @@
 
 namespace libcamera {
 
+class BufferPool;
 class Camera;
 class CameraManager;
 class DeviceEnumerator;
 class MediaDevice;
+class Request;
 class Stream;
 class StreamConfiguration;
 
@@ -45,9 +47,15 @@ public:
 	virtual int configureStreams(Camera *camera,
 				     std::map<Stream *, StreamConfiguration> &config) = 0;
 
+	virtual std::map<Stream *, BufferPool *> allocateBuffers(Camera *camera,
+			std::map<Stream *, StreamConfiguration> &config) = 0;
+	virtual int freeBuffers(Camera *camera) = 0;
+
 	virtual int start(const Camera *camera) = 0;
 	virtual void stop(const Camera *camera) = 0;
 
+	virtual int queueRequest(const Camera *camera, Request *request) = 0;
+
 	virtual bool match(DeviceEnumerator *enumerator) = 0;
 
 protected:
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 3bf196051f2ebdbc..881afe3a4779f46d 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -34,9 +34,16 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	std::map<Stream *, BufferPool *>
+	allocateBuffers(Camera *camera,
+			std::map<Stream *, StreamConfiguration> &config) override;
+	int freeBuffers(Camera *camera) override;
+
 	int start(const Camera *camera) override;
 	void stop(const Camera *camera) override;
 
+	int queueRequest(const Camera *camera, Request *request) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -107,6 +114,18 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
 	return 0;
 }
 
+std::map<Stream *, BufferPool *>
+PipelineHandlerIPU3::allocateBuffers(Camera *camera,
+				     std::map<Stream *, StreamConfiguration> &config)
+{
+	return std::map<Stream *, BufferPool *> {};
+}
+
+int PipelineHandlerIPU3::freeBuffers(Camera *camera)
+{
+	return 0;
+}
+
 int PipelineHandlerIPU3::start(const Camera *camera)
 {
 	LOG(IPU3, Error) << "TODO: start camera";
@@ -118,6 +137,11 @@ void PipelineHandlerIPU3::stop(const Camera *camera)
 	LOG(IPU3, Error) << "TODO: stop camera";
 }
 
+int PipelineHandlerIPU3::queueRequest(const Camera *camera, Request *request)
+{
+	return 0;
+}
+
 bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch cio2_dm("ipu3-cio2");
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index e6a15c58a63cf76b..8b3f0ce7e2112564 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -30,9 +30,16 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	std::map<Stream *, BufferPool *>
+	allocateBuffers(Camera *camera,
+			std::map<Stream *, StreamConfiguration> &config) override;
+	int freeBuffers(Camera *camera) override;
+
 	int start(const Camera *camera) override;
 	void stop(const Camera *camera) override;
 
+	int queueRequest(const Camera *camera, Request *request) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -85,6 +92,18 @@ int PipelineHandlerUVC::configureStreams(Camera *camera,
 	return 0;
 }
 
+std::map<Stream *, BufferPool *>
+PipelineHandlerUVC::allocateBuffers(Camera *camera,
+				    std::map<Stream *, StreamConfiguration> &config)
+{
+	return std::map<Stream *, BufferPool *> {};
+}
+
+int PipelineHandlerUVC::freeBuffers(Camera *camera)
+{
+	return 0;
+}
+
 int PipelineHandlerUVC::start(const Camera *camera)
 {
 	LOG(UVC, Error) << "TODO: start camera";
@@ -96,6 +115,11 @@ void PipelineHandlerUVC::stop(const Camera *camera)
 	LOG(UVC, Error) << "TODO: stop camera";
 }
 
+int PipelineHandlerUVC::queueRequest(const Camera *camera, Request *request)
+{
+	return 0;
+}
+
 bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("uvcvideo");
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index 11eca0cd4d9a6e0c..23a8250ec8b691b5 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -30,9 +30,16 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	std::map<Stream *, BufferPool *>
+	allocateBuffers(Camera *camera,
+			std::map<Stream *, StreamConfiguration> &config) override;
+	int freeBuffers(Camera *camera) override;
+
 	int start(const Camera *camera) override;
 	void stop(const Camera *camera) override;
 
+	int queueRequest(const Camera *camera, Request *request) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -80,6 +87,18 @@ int PipeHandlerVimc::configureStreams(Camera *camera,
 	return 0;
 }
 
+std::map<Stream *, BufferPool *>
+PipeHandlerVimc::allocateBuffers(Camera *camera,
+				 std::map<Stream *, StreamConfiguration> &config)
+{
+	return std::map<Stream *, BufferPool *> {};
+}
+
+int PipeHandlerVimc::freeBuffers(Camera *camera)
+{
+	return 0;
+}
+
 int PipeHandlerVimc::start(const Camera *camera)
 {
 	LOG(VIMC, Error) << "TODO: start camera";
@@ -91,6 +110,11 @@ void PipeHandlerVimc::stop(const Camera *camera)
 	LOG(VIMC, Error) << "TODO: stop camera";
 }
 
+int PipeHandlerVimc::queueRequest(const Camera *camera, Request *request)
+{
+	return 0;
+}
+
 bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("vimc");
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index fa5f780cea34fc8f..7df115cfcb90c83a 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -109,6 +109,39 @@ PipelineHandler::~PipelineHandler()
  * \return 0 on success or a negative error code on error.
  */
 
+/**
+ * \fn PipelineHandler::allocateBuffers()
+ * \brief Allocate buffers for a group of streams
+ * \param[in] camera The camera to allocate buffer for
+ * \param[in] config The stream setup and format describing the buffers
+ *
+ * After a camera's format have been configure and before a camera can be
+ * started buffers needs to be associated with it. Allocation new buffers from
+ * the streams involved in the captured is one option to associated buffers
+ * with a capture.
+ *
+ * The intended caller of this interface is the Camera class which is
+ * responsible for configure the streams and formats of a capture sessions
+ * as well as making sure there are buffers available to actually start the
+ * camera.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
+/**
+ * \fn PipelineHandler::freeBuffers()
+ * \brief Free all buffers associated to a camera
+ * \param[in] camera The camera to free all buffers from
+ *
+ * After a capture session have been stopped all buffers associated with the
+ * camera needs to be freed to allow the memory to be reused in future capture
+ * sessions. The intended caller of this interface is the Camera object
+ * responsible for stopping the camera and once it's stopped freeing its
+ * resources.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
 /**
  * \fn PipelineHandler::start()
  * \brief Start capturing from a group of streams
@@ -136,6 +169,20 @@ PipelineHandler::~PipelineHandler()
  * that the camera was stopped before they could be processed.
  */
 
+/**
+ * \fn PipelineHandler::queueRequest()
+ * \brief Queue a request to the camera
+ * \param[in] camera The camera to queue request on
+ * \param[in] request The request to queue
+ *
+ * Each request the camera should handle needs to be queued to the hardware
+ * thru the pipeline handler. The pipeline handler needs to examine the request,
+ * apply the requested controls with the V4L2 request and queue the buffers
+ * contained in the request to the correct video device.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
 /**
  * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
  * \brief Match media devices and create camera instances