diff --git a/Documentation/devicetree/bindings/iommu/apple,dart.yaml b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
index 94aa9e9afa596d457f1c0f3be71056db70ac8e67..82ad669feef70b470661a5da83827046d9bd1772 100644
--- a/Documentation/devicetree/bindings/iommu/apple,dart.yaml
+++ b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
@@ -41,6 +41,9 @@ properties:
       Has to be one. The single cell describes the stream id emitted by
       a master to the IOMMU.
 
+  power-domains:
+    maxItems: 1
+
 required:
   - compatible
   - reg