[media] media: Media Controller fix to not let stream_count go negative

Change media_entity_pipeline_stop() to not decrement
stream_count of an inactive media pipeline. Doing so,
results in preventing starting the pipeline.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-entity.c

@@ -452,9 +452,12 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
 	media_entity_graph_walk_start(graph, entity_err);
 
 	while ((entity_err = media_entity_graph_walk_next(graph))) {
+		/* don't let the stream_count go negative */
+		if (entity->stream_count > 0) {
 			entity_err->stream_count--;
 			if (entity_err->stream_count == 0)
 				entity_err->pipe = NULL;
+		}
 
 		/*
 		 * We haven't increased stream_count further than this
@@ -486,10 +489,13 @@ void media_entity_pipeline_stop(struct media_entity *entity)
 	media_entity_graph_walk_start(graph, entity);
 
 	while ((entity = media_entity_graph_walk_next(graph))) {
+		/* don't let the stream_count go negative */
+		if (entity->stream_count > 0) {
 			entity->stream_count--;
 			if (entity->stream_count == 0)
 				entity->pipe = NULL;
 		}
+	}
 
 	if (!--pipe->streaming_count)
 		media_entity_graph_walk_cleanup(graph);