v4l: vsp1: Fill display list headers without holding dlm spinlock

The display list headers are filled using information from the display
list only. Lower the display list manager spinlock contention by filling
the headers without holding the lock.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/vsp1/vsp1_dl.c

@@ -483,8 +483,6 @@ void vsp1_dl_list_commit(struct vsp1_dl_list *dl)
 	unsigned long flags;
 	bool update;
 
-	spin_lock_irqsave(&dlm->lock, flags);
-
 	if (dl->dlm->mode == VSP1_DL_MODE_HEADER) {
 		struct vsp1_dl_list *dl_child;
 
@@ -501,7 +499,11 @@ void vsp1_dl_list_commit(struct vsp1_dl_list *dl)
 
 			vsp1_dl_list_fill_header(dl_child, last);
 		}
+	}
 
+	spin_lock_irqsave(&dlm->lock, flags);
+
+	if (dl->dlm->mode == VSP1_DL_MODE_HEADER) {
 		/*
 		 * Commit the head display list to hardware. Chained headers
 		 * will auto-start.