diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
index e04e2c2e9906..9f0231ca47a3 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
@@ -106,8 +106,20 @@ static int __mxc_isi_crossbar_set_routing(struct v4l2_subdev *sd,
 	if (ret)
 		return ret;
 
-	/* The memory input can be routed to the first pipeline only. */
+	/*
+	 * Validate routes against hardware constraints:
+	 * - SOURCE stream must be 0 (pipes are hardcoded to stream 0)
+	 * - Memory input can only route to the first pipeline
+	 */
 	for_each_active_route(routing, route) {
+		if (route->source_stream != 0) {
+			dev_dbg(xbar->isi->dev,
+				"route to pipe %u must use source_stream=0, got %u\n",
+				route->source_pad - xbar->num_sinks,
+				route->source_stream);
+			return -ENXIO;
+		}
+
 		if (route->sink_pad == xbar->num_sinks - 1 &&
 		    route->source_pad != xbar->num_sinks) {
 			dev_dbg(xbar->isi->dev,