ipa: libipa: Provide a common base for frame contexts

Provide a common FrameContext as a base for IPA modules to inherit from.

This will allow having a common set of parameters for every frame
context managed by the FCQueue implementation.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/ipa/libipa/fc_queue.cpp

@@ -20,6 +20,24 @@ namespace ipa {
  * \brief Queue of per-frame contexts
  */
 
+/**
+ * \struct FrameContext
+ * \brief Context for a frame
+ *
+ * The frame context stores data specific to a single frame processed by the
+ * IPA module. Each frame processed by the IPA module has a context associated
+ * with it, accessible through the Frame Context Queue.
+ *
+ * Fields in the frame context should reflect values and controls associated
+ * with the specific frame as requested by the application, and as configured by
+ * the hardware. Fields can be read by algorithms to determine if they should
+ * update any specific action for this frame, and finally to update the metadata
+ * control lists when the frame is fully completed.
+ *
+ * \var FrameContext::frame
+ * \brief The frame number
+ */
+
 /**
  * \class FCQueue
  * \brief A support class for managing FrameContext instances in IPA modules
@@ -65,6 +83,10 @@ namespace ipa {
  * allowed to overflow, which must be ensured by pipeline handlers never
  * queuing more in-flight requests to the IPA module than the queue size. If an
  * overflow condition is detected, the queue will log a fatal error.
+ *
+ * IPA module-specific frame context implementations shall inherit from the
+ * FrameContext base class to support the minimum required features for a
+ * FrameContext.
  */
 
 /**

src/ipa/libipa/fc_queue.h

@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <stdint.h>
 #include <vector>
 
 #include <libcamera/base/log.h>
@@ -17,6 +18,15 @@ LOG_DECLARE_CATEGORY(FCQueue)
 
 namespace ipa {
 
+template<typename FrameContext>
+class FCQueue;
+
+struct FrameContext {
+private:
+	template<typename T> friend class FCQueue;
+	uint32_t frame;
+};
+
 template<typename FrameContext>
 class FCQueue
 {