[libcamera-devel] [PATCH v5 3/9] ipa: ipu3: Add the functions to the Algorithm class

[Jean-Michel Hautbois]

Introduce three functions in the Algorithm class to manage algorithms:
- configure which is called when IPA is configured only
- prepare called on EventFillParams event at each frame when the request
is queued
- process called on EventStatReady event at each frame completion when
the statistics have been generated.

The existing AGC implementation already has a function named process(),
though it has different arguments. Adding the new virtual process()
interface causes a compiler warning due to the AGC implementation
overloading a virtual function, even though the overload can be resolved
correctly.

Temporarily disable the warning in this commit to maintain bisection
until the AGC is converted to the new interface.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 meson.build                           |  4 ++
 src/ipa/ipu3/algorithms/algorithm.cpp | 71 +++++++++++++++++++++++++++
 src/ipa/ipu3/algorithms/algorithm.h   |  8 +++
 3 files changed, 83 insertions(+)

diff --git a/meson.build b/meson.build
index a49c484f..4a10e2b6 100644
--- a/meson.build
+++ b/meson.build
@@ -108,6 +108,10 @@ if cc.has_argument('-Wno-c99-designator')
     ]
 endif
 
+# Do not warn when a function declaration hides virtual functions from
+# a base class
+cpp_arguments += '-Wno-overloaded-virtual'
+
 c_arguments += common_arguments
 cpp_arguments += common_arguments
 
diff --git a/src/ipa/ipu3/algorithms/algorithm.cpp b/src/ipa/ipu3/algorithms/algorithm.cpp
index dd46846a..3e7e3018 100644
--- a/src/ipa/ipu3/algorithms/algorithm.cpp
+++ b/src/ipa/ipu3/algorithms/algorithm.cpp
@@ -25,6 +25,77 @@ namespace ipa::ipu3 {
  * to manage algorithms regardless of their specific type.
  */
 
+/**
+ * \brief Configure the Algorithm given an IPAConfigInfo
+ * \param[in] context The shared IPA context
+ * \param[in] configInfo The IPA configuration data, received from the pipeline
+ * handler
+ *
+ * Algorithms may implement a configure operation to pre-calculate
+ * parameters prior to commencing streaming.
+ *
+ * Configuration state may be stored in the IPASessionConfiguration structure of
+ * the IPAContext.
+ *
+ * \return 0 if successful, an error code otherwise
+ */
+int Algorithm::configure([[maybe_unused]] IPAContext &context,
+			 [[maybe_unused]] const IPAConfigInfo &configInfo)
+{
+	return 0;
+}
+
+/**
+ * \brief Fill the \a params buffer with ISP processing parameters for a frame
+ * \param[in] context The shared IPA context
+ * \param[out] params The IPU3 specific parameters.
+ *
+ * This function is called for every frame when the camera is running before it
+ * is processed by the ImgU to prepare the ImgU processing parameters for that
+ * frame.
+ *
+ * Algorithms shall fill in the parameter structure fields appropriately to
+ * configure the ImgU processing blocks that they are responsible for. This
+ * includes setting fields and flags that enable those processing blocks.
+ */
+void Algorithm::prepare([[maybe_unused]] IPAContext &context,
+			[[maybe_unused]] ipu3_uapi_params *params)
+{
+}
+
+/**
+ * \brief Process ISP statistics, and run algorithm operations
+ * \param[in] context The shared IPA context
+ * \param[in] stats The IPU3 statistics and ISP results
+ *
+ * This function is called while camera is running for every frame processed by
+ * the ImgU, to process statistics generated from that frame by the ImgU.
+ * Algorithms shall use this data to run calculations and update their state
+ * accordingly.
+ *
+ * Processing shall not take an undue amount of time, and any extended or
+ * computationally expensive calculations or operations must be handled
+ * asynchronously in a separate thread.
+ *
+ * Algorithms can store state in their respective IPAFrameContext structures,
+ * and reference state from the IPAFrameContext of other algorithms.
+ *
+ * \todo Historical data may be required as part of the processing.
+ * Either the previous frame, or the IPAFrameContext state of the frame
+ * that generated the statistics for this operation may be required for
+ * some advanced algorithms to prevent oscillations or support control
+ * loops correctly. Only a single IPAFrameContext is available currently,
+ * and so any data stored may represent the results of the previously
+ * completed operations.
+ *
+ * Care shall be taken to ensure the ordering of access to the information
+ * such that the algorithms use up to date state as required.
+ */
+void Algorithm::process([[maybe_unused]] IPAContext &context,
+			[[maybe_unused]] const ipu3_uapi_stats_3a *stats)
+{
+}
+
 } /* namespace ipa::ipu3 */
 
 } /* namespace libcamera */
diff --git a/src/ipa/ipu3/algorithms/algorithm.h b/src/ipa/ipu3/algorithms/algorithm.h
index 072f01c4..43f5d8b0 100644
--- a/src/ipa/ipu3/algorithms/algorithm.h
+++ b/src/ipa/ipu3/algorithms/algorithm.h
@@ -7,6 +7,10 @@
 #ifndef __LIBCAMERA_IPA_IPU3_ALGORITHM_H__
 #define __LIBCAMERA_IPA_IPU3_ALGORITHM_H__
 
+#include <libcamera/ipa/ipu3_ipa_interface.h>
+
+#include "ipa_context.h"
+
 namespace libcamera {
 
 namespace ipa::ipu3 {
@@ -15,6 +19,10 @@ class Algorithm
 {
 public:
 	virtual ~Algorithm() {}
+
+	virtual int configure(IPAContext &context, const IPAConfigInfo &configInfo);
+	virtual void prepare(IPAContext &context, ipu3_uapi_params *params);
+	virtual void process(IPAContext &context, const ipu3_uapi_stats_3a *stats);
 };
 
 } /* namespace ipa::ipu3 */
-- 
2.30.2