libcamera: pipeline_handler: Fix requestComplete on waiting requests on stop

The requestComplete signal is not emitted when the camera is stopped and
the request is still in the waitingRequests_ queue. Fix that by calling
doQueueRequest() on the waiting requests after marking them as
cancelled. This ensures that the requests gets a proper sequence number
and are added to the queuedRequests_ list. This list is then iterated in
completeRequest() and leads to the requestComplete signal.

Closes: https://gitlab.freedesktop.org/camera/libcamera/-/issues/281
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

src/libcamera/pipeline_handler.cpp

@@ -380,7 +380,16 @@ void PipelineHandler::stop(Camera *camera)
 	while (!waitingRequests.empty()) {
 		Request *request = waitingRequests.front();
 		waitingRequests.pop();
-		cancelRequest(request);
+
+		/*
+		 * Cancel all requests by marking them as cancelled and calling
+		 * doQueueRequest() instead of cancelRequest(). This ensures
+		 * that the requests get a sequence number and are temporarily
+		 * added to queuedRequests_ so they can be properly completed in
+		 * completeRequest().
+		 */
+		request->_d()->cancel();
+		doQueueRequest(request);
 	}
 
 	/* Make sure no requests are pending. */