pipeline: raspberrypi: Use an unordered_map for the stream buffer list

By using a map container, we can easily insert/remove buffers from the
buffer list. This will be required to track buffers allocated externally
and passed to the pipeline handler through a Request.

Replace the buffer index tracking with an id generated internally by the
stream object.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

3 files changed, 82 insertions, 35 deletions

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 7d91188c..51544233 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -890,7 +890,6 @@ int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
 int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 {
 	RPiCameraData *data = cameraData(camera);
-	unsigned int index;
 	int ret;
 
 	/*
@@ -917,18 +916,14 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 	 * This will allow us to identify buffers passed between the pipeline
 	 * handler and the IPA.
 	 */
-	index = 0;
 	for (auto const &b : data->isp_[Isp::Stats].getBuffers()) {
-		data->ipaBuffers_.push_back({ .id = RPiIpaMask::STATS | index,
-					      .planes = b->planes() });
-		index++;
+		data->ipaBuffers_.push_back({ .id = RPiIpaMask::STATS | b.first,
+					      .planes = b.second->planes() });
 	}
 
-	index = 0;
 	for (auto const &b : data->unicam_[Unicam::Embedded].getBuffers()) {
-		data->ipaBuffers_.push_back({ .id = RPiIpaMask::EMBEDDED_DATA | index,
-					      .planes = b->planes() });
-		index++;
+		data->ipaBuffers_.push_back({ .id = RPiIpaMask::EMBEDDED_DATA | b.first,
+					      .planes = b.second->planes() });
 	}
 
 	data->ipa_->mapBuffers(data->ipaBuffers_);
@@ -1127,7 +1122,7 @@ void RPiCameraData::unicamBufferDequeue(FrameBuffer *buffer)
 		return;
 
 	for (RPi::RPiStream &s : unicam_) {
-		index = s.getBufferIndex(buffer);
+		index = s.getBufferId(buffer);
 		if (index != -1) {
 			stream = &s;
 			break;
@@ -1178,7 +1173,7 @@ void RPiCameraData::ispInputDequeue(FrameBuffer *buffer)
 		return;
 
 	LOG(RPI, Debug) << "Stream ISP Input buffer complete"
-			<< ", buffer id " << unicam_[Unicam::Image].getBufferIndex(buffer)
+			<< ", buffer id " << unicam_[Unicam::Image].getBufferId(buffer)
 			<< ", timestamp: " << buffer->metadata().timestamp;
 
 	/* The ISP input buffer gets re-queued into Unicam. */
@@ -1195,7 +1190,7 @@ void RPiCameraData::ispOutputDequeue(FrameBuffer *buffer)
 		return;
 
 	for (RPi::RPiStream &s : isp_) {
-		index = s.getBufferIndex(buffer);
+		index = s.getBufferId(buffer);
 		if (index != -1) {
 			stream = &s;
 			break;
@@ -1436,16 +1431,16 @@ void RPiCameraData::tryRunPipeline()
 	/* Set our state to say the pipeline is active. */
 	state_ = State::Busy;
 
-	unsigned int bayerIndex = unicam_[Unicam::Image].getBufferIndex(bayerBuffer);
-	unsigned int embeddedIndex = unicam_[Unicam::Embedded].getBufferIndex(embeddedBuffer);
+	unsigned int bayerId = unicam_[Unicam::Image].getBufferId(bayerBuffer);
+	unsigned int embeddedId = unicam_[Unicam::Embedded].getBufferId(embeddedBuffer);
 
 	LOG(RPI, Debug) << "Signalling RPI_IPA_EVENT_SIGNAL_ISP_PREPARE:"
-			<< " Bayer buffer id: " << bayerIndex
-			<< " Embedded buffer id: " << embeddedIndex;
+			<< " Bayer buffer id: " << bayerId
+			<< " Embedded buffer id: " << embeddedId;
 
 	op.operation = RPI_IPA_EVENT_SIGNAL_ISP_PREPARE;
-	op.data = { RPiIpaMask::EMBEDDED_DATA | embeddedIndex,
-		    RPiIpaMask::BAYER_DATA | bayerIndex };
+	op.data = { RPiIpaMask::EMBEDDED_DATA | embeddedId,
+		    RPiIpaMask::BAYER_DATA | bayerId };
 	ipa_->processEvent(op);
 }
 
diff --git a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
index 80170d64..aee0aa2d 100644
--- a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
+++ b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
@@ -44,26 +44,28 @@ bool RPiStream::isExternal() const
 
 void RPiStream::setExportedBuffers(std::vector<std::unique_ptr<FrameBuffer>> *buffers)
 {
-	std::transform(buffers->begin(), buffers->end(), std::back_inserter(bufferList_),
-		       [](std::unique_ptr<FrameBuffer> &b) { return b.get(); });
+	for (auto const &buffer : *buffers)
+		bufferMap_.emplace(id_.get(), buffer.get());
 }
 
-const std::vector<FrameBuffer *> &RPiStream::getBuffers() const
+const BufferMap &RPiStream::getBuffers() const
 {
-	return bufferList_;
+	return bufferMap_;
 }
 
-int RPiStream::getBufferIndex(FrameBuffer *buffer) const
+int RPiStream::getBufferId(FrameBuffer *buffer) const
 {
 	if (importOnly_)
 		return -1;
 
-	/* Find the buffer in the list, and return the index position. */
-	auto it = std::find(bufferList_.begin(), bufferList_.end(), buffer);
-	if (it != bufferList_.end())
-		return std::distance(bufferList_.begin(), it);
+	/* Find the buffer in the map, and return the buffer id. */
+	auto it = std::find_if(bufferMap_.begin(), bufferMap_.end(),
+			       [&buffer](auto const &p) { return p.second == buffer; });
 
-	return -1;
+	if (it == bufferMap_.end())
+		return -1;
+
+	return it->first;
 }
 
 int RPiStream::prepareBuffers(unsigned int count)
@@ -86,7 +88,7 @@ int RPiStream::prepareBuffers(unsigned int count)
 		}
 
 		/* We must import all internal/external exported buffers. */
-		count = bufferList_.size();
+		count = bufferMap_.size();
 	}
 
 	return dev_->importBuffers(count);
@@ -139,6 +141,9 @@ void RPiStream::returnBuffer(FrameBuffer *buffer)
 	/* Push this buffer back into the queue to be used again. */
 	availableBuffers_.push(buffer);
 
+	/* Allow the buffer id to be reused. */
+	id_.release(getBufferId(buffer));
+
 	/*
 	 * Do we have any Request buffers that are waiting to be queued?
 	 * If so, do it now as availableBuffers_ will not be empty.
@@ -196,12 +201,13 @@ void RPiStream::clearBuffers()
 	availableBuffers_ = std::queue<FrameBuffer *>{};
 	requestBuffers_ = std::queue<FrameBuffer *>{};
 	internalBuffers_.clear();
-	bufferList_.clear();
+	bufferMap_.clear();
+	id_.reset();
 }
 
 int RPiStream::queueToDevice(FrameBuffer *buffer)
 {
-	LOG(RPISTREAM, Debug) << "Queuing buffer " << getBufferIndex(buffer)
+	LOG(RPISTREAM, Debug) << "Queuing buffer " << getBufferId(buffer)
 			      << " for " << name_;
 
 	int ret = dev_->queueBuffer(buffer);
diff --git a/src/libcamera/pipeline/raspberrypi/rpi_stream.h b/src/libcamera/pipeline/raspberrypi/rpi_stream.h
index 959e9147..df986367 100644
--- a/src/libcamera/pipeline/raspberrypi/rpi_stream.h
+++ b/src/libcamera/pipeline/raspberrypi/rpi_stream.h
@@ -9,8 +9,10 @@
 
 #include <queue>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
+#include <libcamera/ipa/raspberrypi.h>
 #include <libcamera/stream.h>
 
 #include "libcamera/internal/v4l2_videodevice.h"
@@ -19,6 +21,8 @@ namespace libcamera {
 
 namespace RPi {
 
+using BufferMap = std::unordered_map<unsigned int, FrameBuffer *>;
+
 /*
  * Device stream abstraction for either an internal or external stream.
  * Used for both Unicam and the ISP.
@@ -27,12 +31,13 @@ class RPiStream : public Stream
 {
 public:
 	RPiStream()
+		: id_(RPiIpaMask::ID)
 	{
 	}
 
 	RPiStream(const char *name, MediaEntity *dev, bool importOnly = false)
 		: external_(false), importOnly_(importOnly), name_(name),
-		  dev_(std::make_unique<V4L2VideoDevice>(dev))
+		  dev_(std::make_unique<V4L2VideoDevice>(dev)), id_(RPiIpaMask::ID)
 	{
 	}
 
@@ -45,8 +50,8 @@ public:
 	bool isExternal() const;
 
 	void setExportedBuffers(std::vector<std::unique_ptr<FrameBuffer>> *buffers);
-	const std::vector<FrameBuffer *> &getBuffers() const;
-	int getBufferIndex(FrameBuffer *buffer) const;
+	const BufferMap &getBuffers() const;
+	int getBufferId(FrameBuffer *buffer) const;
 
 	int prepareBuffers(unsigned int count);
 	int queueBuffer(FrameBuffer *buffer);
@@ -56,6 +61,44 @@ public:
 	void releaseBuffers();
 
 private:
+	class IdGenerator
+	{
+	public:
+		IdGenerator(int max)
+			: max_(max), id_(0)
+		{
+		}
+
+		int get()
+		{
+			int id;
+			if (!recycle_.empty()) {
+				id = recycle_.front();
+				recycle_.pop();
+			} else {
+				id = id_++;
+				ASSERT(id_ <= max_);
+			}
+			return id;
+		}
+
+		void release(int id)
+		{
+			recycle_.push(id);
+		}
+
+		void reset()
+		{
+			id_ = 0;
+			recycle_ = {};
+		}
+
+	private:
+		int max_;
+		int id_;
+		std::queue<int> recycle_;
+	};
+
 	void clearBuffers();
 	int queueToDevice(FrameBuffer *buffer);
 
@@ -74,8 +117,11 @@ private:
 	/* The actual device stream. */
 	std::unique_ptr<V4L2VideoDevice> dev_;
 
+	/* Tracks a unique id key for the bufferMap_ */
+	IdGenerator id_;
+
 	/* All frame buffers associated with this device stream. */
-	std::vector<FrameBuffer *> bufferList_;
+	BufferMap bufferMap_;
 
 	/*
 	 * List of frame buffers that we can use if none have been provided by