diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
index a7f5f5afa0e6..985d7083df9f 100644
--- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
@@ -56,6 +56,11 @@ Additional required properties for imx7d-pcie and imx8mq-pcie:
 	       - "turnoff"
 - fsl,imx7d-pcie-phy: A phandle to an fsl,imx7d-pcie-phy node.
 
+Additional optional properties for imx7d-pcie:
+- fsl,pcie-phy-refclk-internal: If present then an internal PLL input is used
+  as PCIe PHY reference clock source. By default an external ocsillator input
+  is used.
+
 Additional required properties for imx8mq-pcie:
 - clock-names: Must include the following additional entries:
 	- "pcie_aux"