diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
index 2a5d91024059..29bcbd88f457 100644
--- a/Documentation/devicetree/bindings/pci/pci.txt
+++ b/Documentation/devicetree/bindings/pci/pci.txt
@@ -27,6 +27,11 @@ driver implementation may support the following properties:
 - reset-gpios:
    If present this property specifies PERST# GPIO. Host drivers can parse the
    GPIO and apply fundamental reset to endpoints.
+- supports-clkreq:
+   If present this property specifies that CLKREQ signal routing exists from
+   root port to downstream device and host bridge drivers can do programming
+   which depends on CLKREQ signal existence. For example, programming root port
+   not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal.
 
 PCI-PCI Bridge properties
 -------------------------