From: Kory Maincent <kory.maincent@bootlin.com>

Add property to select the preferred hardware timestamp layer.
The choice of using devicetree binding has been made as the PTP precision
and quality depends of external things, like adjustable clock, or the lack
of a temperature compensated crystal or specific features. Even if the
preferred timestamp is a configuration it is hardly related to the design
of the board.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
---
 Documentation/devicetree/bindings/net/ethernet-phy.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
index ad808e9ce5b9..3ea6d2a59ff7 100644
--- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
@@ -144,6 +144,13 @@ properties:
       Mark the corresponding energy efficient ethernet mode as
       broken and request the ethernet to stop advertising it.
 
+  preferred-timestamp:
+    enum:
+      - phy
+      - mac
+    description:
+      Specifies the preferred hardware timestamp layer.
+
   pses:
     $ref: /schemas/types.yaml#/definitions/phandle-array
     maxItems: 1
-- 
2.25.1