misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports wrong speed

["stranche%free.fr@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60038
>Category:       misc
>Synopsis:       Thinkpad X270 with Ethernet on USBC ifconfig reports wrong speed
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 25 11:55:02 +0000 2026
>Originator:     Stephane Tranchemer
>Release:        10.1
>Organization:
-
>Environment:
NetBSD lenonetbsd.mydomain 10.1 NetBSD 10.1 (GENERIC) #0: Mon Dec 16 13:08:11 UTC 2024  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Seen on a Lenovo Thinkpad X270 with Ethernet adapter on USBC.

NetBSD 10.1

dmesg output is correct with a 1000Mbps link:

> $ dmesg | grep ure0
> [     3.055330] ure0 at uhub2 port 4
> [     3.085326] ure0: Realtek (0x0bda) USB 10/100/1000 LAN (0x8153), rev 3.20/31.fd, addr 3
> [     3.115327] ure0: RTL8153 unknown ver 6010
> [     3.215326] rgephy0 at ure0 phy 0: RTL8251 1000BASE-T media interface, rev. 0
> [     3.275326] ure0: Ethernet address 00:e0:de:ad:be:ef

ifconfig reports wrong speed, 100Mbps instead of Gigabit.

> $ ifconfig ure0
> ure0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> capabilities=0x2aa00<IP4CSUM_Tx,TCP4CSUM_Tx,UDP4CSUM_Tx,TCP6CSUM_Tx>
>         capabilities=0x2aa00<UDP6CSUM_Tx>
>         enabled=0
>         ec_capabilities=0x1<VLAN_MTU>
>         ec_enabled=0
>         address: 00:e0:de:ad:be:ef
>         media: Ethernet autoselect (100baseTX full-duplex)
>         status: active
>         inet6 fe80::aa8a:49e:dead:beef%ure0/64 flags 0 scopeid 0x2
>         inet6 2405:de:ad:be:ef::10/64 flags 0x40<AUTOCONF>
>         inet 192.168.54.215/24 broadcast 192.168.54.255 flags 0

An iperf with another machine on the LAN shows speed definitely beyond a 100Mbps link

> $ iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size:  128 KByte (default)
> ------------------------------------------------------------
> [  1] local 192.168.54.10 port 5001 connected with 192.168.54.215 port 65535
> [ ID] Interval       Transfer     Bandwidth
> [  1] 0.00-10.05 sec  55.5 MBytes  46.3 Mbits/sec


>How-To-Repeat:
Link a USB-C ethernet adapter on the machine
>Fix:
unknown