[libcamera-devel] [RFC 1/7] libcamera: pipelines: implement start and stop of a camera

[Niklas Söderlund]

The camera need methods to start and stop capturing once it have been
configured. Extend the pipeline API to provide this and implement stubs
in all pipeline handlers.

Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
---
 src/libcamera/include/pipeline_handler.h |  3 +++
 src/libcamera/pipeline/ipu3/ipu3.cpp     | 14 ++++++++++++
 src/libcamera/pipeline/uvcvideo.cpp      | 14 ++++++++++++
 src/libcamera/pipeline/vimc.cpp          | 14 ++++++++++++
 src/libcamera/pipeline_handler.cpp       | 27 ++++++++++++++++++++++++
 5 files changed, 72 insertions(+)

diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index b4321f0fa0f765be..4bfe45aaf78e34ab 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -45,6 +45,9 @@ public:
 	virtual int configureStreams(Camera *camera,
 				     std::map<Stream *, StreamConfiguration> &config) = 0;
 
+	virtual int start(const Camera *camera) = 0;
+	virtual void stop(const Camera *camera) = 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 7823bbb55d9bde16..3bf196051f2ebdbc 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -34,6 +34,9 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	int start(const Camera *camera) override;
+	void stop(const Camera *camera) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -104,6 +107,17 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
 	return 0;
 }
 
+int PipelineHandlerIPU3::start(const Camera *camera)
+{
+	LOG(IPU3, Error) << "TODO: start camera";
+	return 0;
+}
+
+void PipelineHandlerIPU3::stop(const Camera *camera)
+{
+	LOG(IPU3, Error) << "TODO: stop camera";
+}
+
 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 ad4d45d0698519b6..e6a15c58a63cf76b 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -30,6 +30,9 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	int start(const Camera *camera) override;
+	void stop(const Camera *camera) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -82,6 +85,17 @@ int PipelineHandlerUVC::configureStreams(Camera *camera,
 	return 0;
 }
 
+int PipelineHandlerUVC::start(const Camera *camera)
+{
+	LOG(UVC, Error) << "TODO: start camera";
+	return 0;
+}
+
+void PipelineHandlerUVC::stop(const Camera *camera)
+{
+	LOG(UVC, Error) << "TODO: stop camera";
+}
+
 bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("uvcvideo");
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index 900477e257232b70..11eca0cd4d9a6e0c 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -30,6 +30,9 @@ public:
 	int configureStreams(Camera *camera,
 			     std::map<Stream *, StreamConfiguration> &config) override;
 
+	int start(const Camera *camera) override;
+	void stop(const Camera *camera) override;
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -77,6 +80,17 @@ int PipeHandlerVimc::configureStreams(Camera *camera,
 	return 0;
 }
 
+int PipeHandlerVimc::start(const Camera *camera)
+{
+	LOG(VIMC, Error) << "TODO: start camera";
+	return 0;
+}
+
+void PipeHandlerVimc::stop(const Camera *camera)
+{
+	LOG(VIMC, Error) << "TODO: stop camera";
+}
+
 bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("vimc");
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 3a560e10c442717f..fa5f780cea34fc8f 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -109,6 +109,33 @@ PipelineHandler::~PipelineHandler()
  * \return 0 on success or a negative error code on error.
  */
 
+/**
+ * \fn PipelineHandler::start()
+ * \brief Start capturing from a group of streams
+ * \param[in] camera The camera to start
+ *
+ * Start the group of streams that have been configured for capture by
+ * \a configureStreams(). The intended caller of this interface is
+ * the Camera class which will in turn will receive the call from the
+ * application to indicate that it's done configuring the streams
+ * and are ready to capture.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
+/**
+ * \fn PipelineHandler::stop()
+ * \brief Stop capturing from all running streams
+ * \param[in] camera The camera to stop
+ *
+ * Stop processing requests, finish processing all already queued requests
+ * and once all buffers on all streams have been dequeued stop capturing
+ * from all running streams. Finish processing of queued requests do not
+ * necessarily involve processing them by the capture hardware but notifying
+ * the application that a queued request was not processed due to the fact
+ * that the camera was stopped before they could be processed.
+ */
+
 /**
  * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
  * \brief Match media devices and create camera instances
-- 
2.20.1