[FS#670] whr-1166d gigabit port not working

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Robin Panda (andapanda) 

Attached to Project - LEDE Project
Summary - whr-1166d gigabit port not working
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Medium
Priority - Very Low
Reported Version - lede-17.01
Due in Version - Undecided
Due Date - Undecided
Details - This is on a WHR-1166D running 17.01.
Connections to to the gigabit (WAN) port don't work. The LuCI switch menu shows it connected and the kernel message says link up, but the status page says not connected. The 100mbit ports work fine.

It *DOES* work in OpenWrt CC, but if CC is sysupgraded from LEDE the port still won't work until a power cycle. Soft reboots don't work, so I suspect LEDE is setting something on the switch or phy config that CC leaves at default.

Noticed differences:
Gigabit phy is driver=ICPlus IP1001 on LEDE, generic on CC.
Switch configuration gui in LuCI is different: CC has two extra ports that LEDE doesn't. They're not exposed on the device so it makes sense to hide them. LEDE swconfig shows the "hidden" ports.

Other possibly useful info:
ifconfig shows the port sends packets (perhaps DHCP requests), but never receives anything.
swconfig shows all octets received are bad, but also fewer octets than packets...
Port 5:
        mib: Port 5 MIB counters
TxGPC      : 34472
TxBOC      : 0
TxGOC      : 56561081
TxEPC      : 0
RxGPC      : 3183869952
RxBOC      : 13195604
RxGOC      : 0
RxEPC1     : 0
RxEPC2     : 0

This device has a strange combination where one of the ports on the 7620 is connected to a 10/100 switch, but the other port is used as WAN and connected just to a gigabit phy.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=670