dt-bindings: net: dsa: lantiq,gswip: add support for MII delay properties

Add support for standard tx-internal-delay-ps and rx-internal-delay-ps
properties on port nodes to allow fine-tuning of RGMII clock delays.

The GSWIP switch hardware supports delay values in 500 picosecond
increments from 0 to 3500 picoseconds, with a post-reset default of 2000
picoseconds for both TX and RX delays. The driver currently sets the
delay to 0 in case the PHY is setup to carry out the delay by the
corresponding interface modes ("rgmii-id", "rgmii-rxid", "rgmii-txid").

This corresponds to the driver changes that allow adjusting MII delays
using Device Tree properties instead of relying solely on the PHY
interface mode.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/9e007d4f85c2c6d69e0b91f3663d99e0f6fc8eac.1762170107.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
index 809d0e9d0a15bbe6656f6fca63c6a68563a3ce10..929f6f8e4534b2375060ac0e5cb0cce06ceda3f6 100644 (file)
--- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
@@ -104,6 +104,20 @@ patternProperties:
             description:
               Configure the RMII reference clock to be a clock output
               rather than an input. Only applicable for RMII mode.
+          tx-internal-delay-ps:
+            enum: [0, 500, 1000, 1500, 2000, 2500, 3000, 3500]
+            description:
+              RGMII TX Clock Delay defined in pico seconds.
+              The delay lines adjust the MII clock vs. data timing.
+              If this property is not present the delay is determined by
+              the interface mode.
+          rx-internal-delay-ps:
+            enum: [0, 500, 1000, 1500, 2000, 2500, 3000, 3500]
+            description:
+              RGMII RX Clock Delay defined in pico seconds.
+              The delay lines adjust the MII clock vs. data timing.
+              If this property is not present the delay is determined by
+              the interface mode.
 
 required:
   - compatible
@@ -127,8 +141,10 @@ examples:
                     port@0 {
                             reg = <0>;
                             label = "lan3";
-                            phy-mode = "rgmii";
+                            phy-mode = "rgmii-id";
                             phy-handle = <&phy0>;
+                            tx-internal-delay-ps = <2000>;
+                            rx-internal-delay-ps = <2000>;
                     };
 
                     port@1 {