ARM: dts: pfla02: add ksz9031 clock skew values

This change “ARM: dts: pfla02: add ksz9031 clock skew values” in Linux kernel is authored by Philipp Zabel <p.zabel [at]> on Mon Feb 4 16:29:56 2019 +0100.

ARM: dts: pfla02: add ksz9031 clock skew values

The pfla02 SoM has a Micrel KSZ9031RNX ethernet phy connected to the FEC,
which needs RX and TX clock skew settings to compensate for differences
in line length. The skew values are taken from barebox commit
4c65c20f1071 ("ARM: pfla02: Set new ethernet phy tx timings"), which
is based on patches originally provided by Phytec:

    TX_CLK line is approx. 54mm longer than other TX lines which adds
    a delay of 0.36ns. RGMII need a delay of min. 1.0ns. This mean we
    have to add a delay of 0.64ns. We choose 0.78 to have a little gap.
    This can be done by setting GTX pad skew value to 11100
    Also add a delay for the RX delay lines, needed for the Duallite
    variant.  => Set register 2.8 (RGMII Clock Pad Skew) to 0x039F.

Cc: Christian Hemp <>
Signed-off-by: Philipp Zabel <>
Signed-off-by: Marco Felsch <>
Signed-off-by: Shawn Guo <>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit 8de81c8.

There are 13 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi b/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
index 1bfa41e..433bf09 100644
--- a/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
@@ -89,10 +89,23 @@
 &fec {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_enet>;
+	phy-handle = <ðphy>;
 	phy-mode = "rgmii";
 	phy-reset-gpios = <&gpio3 23 GPIO_ACTIVE_LOW>;
 	phy-supply = <&vdd_eth_io_reg>;
 	status = "disabled";
+	fec_mdio: mdio {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		ethphy: ethernet-phy@0 {
+			compatible = "ethernet-phy-ieee802.3-c22";
+			reg = <0>;
+			txc-skew-ps = <1680>;
+			rxc-skew-ps = <1860>;
+		};
+	};
 &gpmi {

The commit for this change in Linux stable tree is 8de81c8 (patch).

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