[libcamera-devel] [PATCH v3 7/8] libcamera: pipeline: Add method to retrieve Request from Buffer

[Jacopo Mondi]

Add a method to CameraData base class to retrieve a pointer to the
Request that contains a given buffer. Intended users are buffer
completion slots that needs to associate a Request to a just completed
Buffer.

In preparation to support multiple requests from different streams,
update all the pipeline handler implementations to use this method
instead of using the last queued request.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/request.h              |  2 ++
 src/libcamera/include/pipeline_handler.h |  3 +++
 src/libcamera/pipeline/ipu3/ipu3.cpp     |  3 ++-
 src/libcamera/pipeline/uvcvideo.cpp      |  3 ++-
 src/libcamera/pipeline/vimc.cpp          |  3 ++-
 src/libcamera/pipeline_handler.cpp       | 29 ++++++++++++++++++++++++
 src/libcamera/request.cpp                |  7 ++++++
 7 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/include/libcamera/request.h b/include/libcamera/request.h
index 5ac4d20d1d9f..8f5892fd3111 100644
--- a/include/libcamera/request.h
+++ b/include/libcamera/request.h
@@ -38,6 +38,8 @@ public:
 
 	const std::list<Stream *> streams() const;
 
+	const std::unordered_set<Buffer *> &pending() const { return pending_; }
+
 	Status status() const { return status_; }
 
 private:
diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index 920b57609470..6cdadcbdc3ea 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -39,6 +39,9 @@ public:
 	PipelineHandler *pipe_;
 	std::list<Request *> queuedRequests_;
 
+protected:
+	Request *requestFromBuffer(Buffer *buffer);
+
 private:
 	CameraData(const CameraData &) = delete;
 	CameraData &operator=(const CameraData &) = delete;
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 8c67cf985d1e..17e3e8677e28 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -801,7 +801,8 @@ void PipelineHandlerIPU3::IPU3CameraData::imguInputBufferReady(Buffer *buffer)
  */
 void PipelineHandlerIPU3::IPU3CameraData::imguOutputBufferReady(Buffer *buffer)
 {
-	Request *request = queuedRequests_.front();
+	Request *request = requestFromBuffer(buffer);
+	ASSERT(request);
 
 	pipe_->completeBuffer(camera_, request, buffer);
 	pipe_->completeRequest(camera_, request);
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index 128f0c49dba3..d571b8b4ea83 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -226,7 +226,8 @@ bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 
 void PipelineHandlerUVC::UVCCameraData::bufferReady(Buffer *buffer)
 {
-	Request *request = queuedRequests_.front();
+	Request *request = requestFromBuffer(buffer);
+	ASSERT(request);
 
 	pipe_->completeBuffer(camera_, request, buffer);
 	pipe_->completeRequest(camera_, request);
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index 6735940799d8..e83416effad8 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -223,7 +223,8 @@ bool PipelineHandlerVimc::match(DeviceEnumerator *enumerator)
 
 void PipelineHandlerVimc::VimcCameraData::bufferReady(Buffer *buffer)
 {
-	Request *request = queuedRequests_.front();
+	Request *request = requestFromBuffer(buffer);
+	ASSERT(request);
 
 	pipe_->completeBuffer(camera_, request, buffer);
 	pipe_->completeRequest(camera_, request);
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 9a8a4fde57e6..830ff354ed3e 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -86,6 +86,35 @@ LOG_DEFINE_CATEGORY(Pipeline)
  * PipelineHandler::completeRequest()
  */
 
+/**
+ * \brief Retrieve the pending request that contains \a buffer
+ * \param[in] buffer The buffer contained in the returned request
+ *
+ * Return the request that contains \a buffer, or nullptr if no such request
+ * is found. The intended callers of this method are buffer completion slots
+ * implemented in CameraData sub-classes which needs to associated a request
+ * to the just completed buffer. It is up to the caller of this function to
+ * deal with the case the buffer does not belong to any previously queued
+ * request or the request has already completed, possibly because of a
+ * duplicated buffer completion notification. This is generally considered
+ * a fatal error, and callers are expected to assert the validity of the
+ * returned request.
+ *
+ * \return A pointer to the pending Request that contains the Buffer \a buffer,
+ * or nullptr if no such request is found
+ */
+Request *CameraData::requestFromBuffer(Buffer *buffer)
+{
+	for (Request *req : queuedRequests_) {
+		for (Buffer *b : req->pending()) {
+			if (b == buffer)
+				return req;
+		}
+	}
+
+	return nullptr;
+}
+
 /**
  * \class PipelineHandler
  * \brief Create and manage cameras based on a set of media devices
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index 3a7841fb2bb3..c555752b2c0b 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -108,6 +108,13 @@ const std::list<Stream *> Request::streams() const
 	return streams;
 }
 
+/**
+ * \fn Request::pending()
+ * \brief Retrieve the list of not-yet-completed buffers
+ *
+ * \return The set of pending buffers
+ */
+
 /**
  * \fn Request::status()
  * \brief Retrieve the request completion status
-- 
2.21.0