[openwrt/openwrt] ramips: mt7620n: add mdio node and disable port4 by default

[LEDE Commits]

mkresin pushed a commit to openwrt/openwrt.git, branch master:
https://git.lede-project.org/d482356322c9910541a3118d049718b384a252bd

commit d482356322c9910541a3118d049718b384a252bd
Author: Mathias Kresin <dev at kresin.me>
AuthorDate: Tue Mar 13 20:06:37 2018 +0100

    ramips: mt7620n: add mdio node and disable port4 by default
    
    Revert the changes I applied to aa5014dd1a58 ("ramips: mt7620n: enable
    port 4 as EPHY by default").
    
    The driver expects a node mdio-bus to be present, regardless of the
    actual node status. If the node is missing the driver fails to load  with
    
      mtk_soc_eth 10100000.ethernet: no mdio-bus child node found
    
    Disable port4 by default again. If the port is enabled but not present, a
    "invalid port id 4" warning is shown during boot.
    
    Fixes: FS#1428
    
    Signed-off-by: Mathias Kresin <dev at kresin.me>
---
 target/linux/ramips/dts/mt7620n.dtsi | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/target/linux/ramips/dts/mt7620n.dtsi b/target/linux/ramips/dts/mt7620n.dtsi
index 26c7d91..ebaa094 100644
--- a/target/linux/ramips/dts/mt7620n.dtsi
+++ b/target/linux/ramips/dts/mt7620n.dtsi
@@ -293,11 +293,18 @@
 
 		mediatek,switch = <&gsw>;
 
+		mdio-bus {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			status = "disabled";
+		};
+
 		port at 4 {
 			compatible = "mediatek,mt7620a-gsw-port", "mediatek,eth-port";
 			reg = <4>;
 
-			status = "okay";
+			status = "disabled";
 		};
 	};