[libcamera-devel] [PATCH v2 5/6] pipeline: raspberrypi: Add a timeout to free buffers on stopDevice()

[Naushir Patuck]

Start a 5 second timer when stopDevice() is called, and if it times out,
free all internally allocated buffers. The timer is cleared when start() is
subsequently called.

This avoids the pipeline handler from holding onto internal buffers for long
periods of time due to application inactivity.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp        | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index d3212b193ced..32b282b4bdbd 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -15,6 +15,7 @@
 #include <utility>
 
 #include <libcamera/base/shared_fd.h>
+#include <libcamera/base/timer.h>
 #include <libcamera/base/utils.h>
 
 #include <libcamera/camera.h>
@@ -45,6 +46,8 @@
 #include "dma_heaps.h"
 #include "rpi_stream.h"
 
+using namespace std::literals::chrono_literals;
+
 namespace libcamera {
 
 LOG_DEFINE_CATEGORY(RPI)
@@ -288,6 +291,9 @@ public:
 	/* Has this camera been reconfigured? */
 	bool reallocate_;
 
+	/* Timer to free internal buffers once stopDevice() has been called. */
+	Timer stopTimer_;
+
 private:
 	void checkRequestCompleted();
 	void fillRequestMetadata(const ControlList &bufferControls,
@@ -991,6 +997,10 @@ int PipelineHandlerRPi::start(Camera *camera, const ControlList *controls)
 	RPiCameraData *data = cameraData(camera);
 	int ret;
 
+	/* Disable the stop timeout waiting to release buffers after a stop(). */
+	data->stopTimer_.stop();
+	data->stopTimer_.timeout.disconnect();
+
 	for (auto const stream : data->streams_)
 		stream->resetBuffers();
 
@@ -1071,6 +1081,13 @@ void PipelineHandlerRPi::stopDevice(Camera *camera)
 
 	/* Stop the IPA. */
 	data->ipa_->stop();
+
+	/*
+	 * Start a 5 second timer once the camera is stopped, and on a timeout,
+	 * release all internally allocated buffers.
+	 */
+	data->stopTimer_.timeout.connect(data, &RPiCameraData::freeBuffers);
+	data->stopTimer_.start(5s);
 }
 
 int PipelineHandlerRPi::queueRequestDevice(Camera *camera, Request *request)
-- 
2.25.1