libcamera: pipeline_handler: Document requestSequence_

The documentation for requestSequence_ was not added when the sequence
number was implemented.

Provide it.

Fixes: d874b3e341 ("libcamera: request: Provide a sequence number")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/pipeline_handler.cpp

@@ -97,6 +97,17 @@ LOG_DEFINE_CATEGORY(Pipeline)
  * when creating the camera, and shall not be modified afterwards.
  */
 
+/**
+ * \var CameraData::requestSequence_
+ * \brief The queuing sequence of the request
+ *
+ * When requests are queued, they are given a per-camera sequence number to
+ * facilitate debugging of internal request usage.
+ *
+ * The requestSequence_ tracks the number of requests queued to a camera
+ * over its lifetime.
+ */
+
 /**
  * \class PipelineHandler
  * \brief Create and manage cameras based on a set of media devices