@@ -88,16 +88,28 @@ namespace libcamera::ipa::rkisp1 {
* \struct IPAActiveState
* \brief Active state for algorithms
*
- * The active state stores algorithm-specific data that needs to be shared
- * between multiple algorithms and the IPA module. It is accessible through the
- * IPAContext structure.
+ * The active state contains all algorithm-specific data that needs to be
+ * maintained by algorithms across frames. Unlike the session configuration,
+ * the active state is mutable and constantly updated by algorithms. The active
+ * state is accessible through the IPAContext structure.
*
- * \todo Split the data contained in this structure between the active state
- * and the frame contexts.
+ * The active state stores two distinct categories of information:
*
- * Each of the fields in the active state 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.
+ * - The consolidated value of all algorithm controls. Requests passed to
+ * the queueRequest() function store values for controls that the
+ * application wants to modify for that particular frame, and the
+ * queueRequest() function updates the active state with those values.
+ * The active state thus contains a consolidated view of the value of all
+ * controls handled by the algorithm.
+ *
+ * - The value of parameters computed by the algorithm when running in auto
+ * mode. Algorithms running in auto mode compute new parameters every
+ * time statistics buffers are received (either synchronously, or
+ * possibly in a background thread). The latest computed value of those
+ * parameters is stored in the active state in the process() function.
+ *
+ * Each of the members in the active state belongs to a specific algorithm. A
+ * member may be read by any algorithm, but shall only be written by its owner.
*/
/**
@@ -185,7 +197,32 @@ namespace libcamera::ipa::rkisp1 {
* \struct IPAFrameContext
* \brief Per-frame context for algorithms
*
- * \todo Populate the frame context for all algorithms
+ * The frame context stores two distinct categories of information:
+ *
+ * - The value of the controls to be applied to the frame. These values are
+ * typically set in the queueRequest() function, from the consolidated
+ * control values stored in the active state. The frame context thus stores
+ * values for all controls related to the algorithm, not limited to the
+ * controls specified in the corresponding request, but consolidated from all
+ * requests that have been queued so far.
+ *
+ * For controls that can be set manually or computed by an algorithm
+ * (depending on the algorithm operation mode), such as for instance the
+ * colour gains for the AWB algorithm, the control value will be stored in
+ * the frame context in the queueRequest() function only when operating in
+ * manual mode. When operating in auto mode, the values are computed by the
+ * algorithm in process(), stored in the active state, and copied to the
+ * frame context in prepare(), just before being stored in the ISP parameters
+ * buffer.
+ *
+ * The queueRequest() function can also store ancillary data in the frame
+ * context, such as flags to indicate if (and what) control values have
+ * changed compared to the previous request.
+ *
+ * - Status information computed by the algorithm for a frame. For instance,
+ * the colour temperature estimated by the AWB algorithm from ISP statistics
+ * calculated on a frame is stored in the frame context for that frame in
+ * the process() function.
*/
/**