ipa: ipu3: Introduce a Context structure

An increasing amount of data and information needs to be shared between
the components that build up to implement image processing algorithms.

Create a context structure which will allow us to work towards calling
algorithms in a modular way, and sharing information between the modules.

The IPA context is a global context set at configure time
(IPASessionConfiguration) and a per-frame context (IPAFrameContext) used
while streaming.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/ipu3/ipa_context.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * ipu3_ipa_context.h - IPU3 IPA Context
+ *
+ */
+#ifndef __LIBCAMERA_IPU3_IPA_CONTEXT_H__
+#define __LIBCAMERA_IPU3_IPA_CONTEXT_H__
+
+#include <linux/intel-ipu3.h>
+
+namespace libcamera {
+
+namespace ipa::ipu3 {
+
+struct IPASessionConfiguration {
+};
+
+struct IPAFrameContext {
+};
+
+struct IPAContext {
+	IPASessionConfiguration configuration;
+	IPAFrameContext frameContext;
+};
+
+} /* namespace ipa::ipu3 */
+
+} /* namespace libcamera*/
+
+#endif /* __LIBCAMERA_IPU3_IPA_CONTEXT_H__ */

src/ipa/ipu3/ipu3.cpp

@@ -33,6 +33,52 @@
 #include "ipu3_awb.h"
 #include "libipa/camera_sensor_helper.h"
 
+/**
+ * \file ipa_context.h
+ * \brief Context and state information shared between the algorithms
+ */
+
+/**
+ * \struct IPASessionConfiguration
+ * \brief Session configuration for the IPA module
+ *
+ * The session configuration contains all IPA configuration parameters that
+ * remain constant during the capture session, from IPA module start to stop.
+ * It is typically set during the configure() operation of the IPA module, but
+ * may also be updated in the start() operation.
+ */
+
+/**
+ * \struct IPAFrameContext
+ * \brief Per-frame context for algorithms
+ *
+ * The frame context stores data specific to a single frame processed by the
+ * IPA. Each frame processed by the IPA has a context associated with it,
+ * accessible through the IPAContext structure.
+ *
+ * \todo Detail how to access contexts for a particular frame
+ *
+ * Each of the fields in the frame context belongs to either a specific
+ * algorithm, or to the top-level IPA module. A field may be read by any
+ * algorithm, but should only be written by its owner.
+ */
+
+/**
+ * \struct IPAContext
+ * \brief Global IPA context data shared between all algorithms
+ *
+ * \var IPAContext::configuration
+ * \brief The IPA session configuration, immutable during the session
+ *
+ * \var IPAContext::frameContext
+ * \brief The frame context for the frame being processed
+ *
+ * \todo While the frame context is supposed to be per-frame, this
+ * single frame context stores data related to both the current frame
+ * and the previous frames, with fields being updated as the algorithms
+ * are run. This needs to be turned into real per-frame data storage.
+ */
+
 static constexpr uint32_t kMaxCellWidthPerSet = 160;
 static constexpr uint32_t kMaxCellHeightPerSet = 56;