[libcamera-devel] [PATCH v4 04/32] ipa: libipa: Introduce FrameContextQueue
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Sep 8 03:41:32 CEST 2022
From: Umang Jain <umang.jain at ideasonboard.com>
Introduce a common implementation in libipa to represent the queue of
frame contexts.
Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
Changes since v3:
- Split the IPU3 changes to a separate patch
- Use composition instead of inheritance
- Use vector instead of array for backend storage
- Make the queue size dynamic
- Rename initialise() to init()
---
src/ipa/libipa/fc_queue.cpp | 117 ++++++++++++++++++++++++++++++++++++
src/ipa/libipa/fc_queue.h | 108 +++++++++++++++++++++++++++++++++
src/ipa/libipa/meson.build | 2 +
3 files changed, 227 insertions(+)
create mode 100644 src/ipa/libipa/fc_queue.cpp
create mode 100644 src/ipa/libipa/fc_queue.h
diff --git a/src/ipa/libipa/fc_queue.cpp b/src/ipa/libipa/fc_queue.cpp
new file mode 100644
index 000000000000..b81d497e255a
--- /dev/null
+++ b/src/ipa/libipa/fc_queue.cpp
@@ -0,0 +1,117 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Google Inc.
+ *
+ * fc_queue.cpp - IPA Frame context queue
+ */
+
+#include "fc_queue.h"
+
+#include <libcamera/base/log.h>
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(FCQueue)
+
+namespace ipa {
+
+/**
+ * \file fc_queue.h
+ * \brief Queue to access per-frame Context
+ */
+
+/**
+ * \class FCQueue
+ * \brief A support class for queueing FrameContext instances through the IPA
+ * \tparam FrameContext The IPA specific FrameContext derived class type
+ *
+ * The frame context queue provides a simple circular buffer implementation to
+ * store IPA specific context for each frame through its lifetime within the
+ * IPA.
+ *
+ * FrameContext instances are expected to be referenced by a monotonically
+ * increasing sequence count corresponding to a frame sequence number.
+ *
+ * A FrameContext is initialised for a given frame when the corresponding
+ * Request is first queued into the IPA. From that point on the FrameContext can
+ * be obtained by the IPA and its algorithms by referencing it from the frame
+ * sequence number.
+ *
+ * A frame sequence number from the image source must correspond to the request
+ * sequence number for this implementation to be supported in an IPA. It is
+ * expected that the same sequence number will be used to reference the context
+ * of the frame from the point of queueing the request, specifying controls for
+ * a given frame, and processing of any ISP related controls and statistics for
+ * the same corresponding image.
+ *
+ * IPA specific frame context implementations shall inherit from the
+ * IPAFrameContext base class to support the minimum required features for a
+ * FrameContext.
+ *
+ * FrameContexts are overwritten when they are recycled and re-initialised by
+ * the first access made on them by either init(frame) or get(frame). It is
+ * required that the number of available slots in the frame context queue is
+ * larger or equal to the maximum number of in-flight requests a pipeline can
+ * handle to avoid overwriting frame context instances that still have to be
+ * processed.
+ *
+ * In the case an application does not queue requests to the camera fast
+ * enough, frames can be produced and processed by the IPA without a
+ * corresponding Request being queued. In this case the IPA algorithm
+ * will try to access the FrameContext with a call to get() before it
+ * had been initialized at queueRequest() time. In this case, there
+ * is no way the controls associated with the late Request could be
+ * applied in time, as the frame as already been processed by the IPA.
+ *
+ * \todo Set an error flag for per-frame control errors.
+ */
+
+/**
+ * \fn FCQueue::FCQueue(unsigned int size)
+ * \brief Construct a frame context queue of a specified size
+ * \param[in] size The number of contexts in the queue
+ */
+
+/**
+ * \fn FCQueue::clear()
+ * \brief Clear the context queue
+ *
+ * Reset the queue and ensure all FrameContext slots are re-initialised.
+ * IPA modules are expected to clear the frame context queue at the beginning of
+ * a new streaming session, in IPAModule::start().
+ */
+
+/**
+ * \fn FCQueue::init(uint32_t frame)
+ * \brief Initialize and return the Frame Context at slot specified by \a frame
+ * \param[in] frame The frame context sequence number
+ *
+ * The first call to obtain a FrameContext from the FCQueue should be handled
+ * through this call. The FrameContext will be initialised for the frame and
+ * returned to the caller if it was not already initialised.
+ *
+ * If the FrameContext was already initialized for this sequence, a warning will
+ * be reported and the previously initialized FrameContext is returned.
+ *
+ * Frame contexts are expected to be initialised when a Request is first passed
+ * to the IPA module in IPAModule::queueRequest().
+ *
+ * \return A reference to the FrameContext for sequence \a frame
+ */
+
+/**
+ * \fn FCQueue::get()
+ * \brief Obtain the Frame Context at slot specified by \a frame
+ * \param[in] frame The frame context sequence number
+ *
+ * Obtains an existing FrameContext from the queue and returns it to the caller.
+ *
+ * If the FrameContext is not correctly initialised for the \a frame, it will be
+ * initialised.
+ *
+ * \return A reference to the FrameContext for sequence \a frame
+ */
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/fc_queue.h b/src/ipa/libipa/fc_queue.h
new file mode 100644
index 000000000000..0f3af0f3a189
--- /dev/null
+++ b/src/ipa/libipa/fc_queue.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Google Inc.
+ *
+ * fc_queue.h - IPA Frame context queue
+ */
+
+#pragma once
+
+#include <algorithm>
+#include <vector>
+
+#include <libcamera/base/log.h>
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(FCQueue)
+
+namespace ipa {
+
+template<typename FrameContext>
+class FCQueue
+{
+public:
+ FCQueue(unsigned int size)
+ : contexts_(size)
+ {
+ }
+
+ void clear()
+ {
+ std::fill(contexts_.begin(), contexts_.end(), FrameContext{});
+ }
+
+ FrameContext &init(const uint32_t frame)
+ {
+ FrameContext &frameContext = contexts_[frame % contexts_.size()];
+
+ /*
+ * Do not re-initialise if a get() call has already fetched this
+ * frame context to preseve the context.
+ *
+ * \todo If the the sequence number of the context to initialise
+ * is smaller than the sequence number of the queue slot to use,
+ * it means that we had a serious request underrun and more
+ * frames than the queue size has been produced since the last
+ * time the application has queued a request. Does this deserve
+ * an error condition ?
+ */
+ if (frame != 0 && frame <= frameContext.frame)
+ LOG(FCQueue, Warning)
+ << "Frame " << frame << " already initialised";
+ else
+ init(frameContext, frame);
+
+ return frameContext;
+ }
+
+ FrameContext &get(uint32_t frame)
+ {
+ FrameContext &frameContext = contexts_[frame % contexts_.size()];
+
+ /*
+ * If the IPA algorithms try to access a frame context slot which
+ * has been already overwritten by a newer context, it means the
+ * frame context queue has overflowed and the desired context
+ * has been forever lost. The pipeline handler shall avoid
+ * queueing more requests to the IPA than the frame context
+ * queue size.
+ */
+ if (frame < frameContext.frame)
+ LOG(FCQueue, Fatal) << "Frame Context for " << frame
+ << " has been overwritten by "
+ << frameContext.frame;
+
+ if (frame == frameContext.frame)
+ return frameContext;
+
+ /*
+ * The frame context has been retrieved before it was
+ * initialised through the initialise() call. This indicates an
+ * algorithm attempted to access a Frame context before it was
+ * queued to the IPA. Controls applied for this request may be
+ * left unhandled.
+ *
+ * \todo Set an error flag for per-frame control errors.
+ */
+ LOG(FCQueue, Warning)
+ << "Obtained an uninitialised FrameContext for " << frame;
+
+ init(frameContext, frame);
+
+ return frameContext;
+ }
+
+private:
+ void init(FrameContext &frameContext, const uint32_t frame)
+ {
+ frameContext = {};
+ frameContext.frame = frame;
+ }
+
+ std::vector<FrameContext> contexts_;
+};
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index fb894bc614af..016b8e0ec9be 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -3,6 +3,7 @@
libipa_headers = files([
'algorithm.h',
'camera_sensor_helper.h',
+ 'fc_queue.h',
'histogram.h',
'module.h',
])
@@ -10,6 +11,7 @@ libipa_headers = files([
libipa_sources = files([
'algorithm.cpp',
'camera_sensor_helper.cpp',
+ 'fc_queue.cpp',
'histogram.cpp',
'module.cpp',
])
--
Regards,
Laurent Pinchart
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