USB to ethernet: fail to transmit any packages

Question

I've a custom embedded linux board with a lan7500i-ABZJ connected over USB.

So I compiled the linux kernel (using buildroot) with the smsc75xx module built in. The startup kernel messages indeed show:

    [    5.315124] usb 1-1: New USB device found, idVendor=0424, idProduct=7500, bcdDevice= 2.00
    [    5.324072] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
    [    5.340746] smsc75xx v1.0.0
    [    5.539195] smsc75xx 1-1:1.0 eth1: register 'smsc75xx' at usb-ci_hdrc.0-1, smsc75xx USB 2.0 Gigabit Ethernet, 8e:64:f6:eb:5e:65

Now I add an IP address:

    ifconfig eth1 192.168.1.44 netmask 255.255.255.0 up

But once I try to ping an adress on the local network, all packets are lost:

    # ping 192.168.1.40
    PING 192.168.1.40 (192.168.1.40): 56 data bytes
    ^C
    --- 192.168.1.40 ping statistics ---
    3 packets transmitted, 0 packets received, 100% packet loss
    # arp
    ? (192.168.1.40) at <incomplete>  on eth1

And no packages are transmitted over the interface:

    eth1      Link encap:Ethernet  HWaddr 8E:64:F6:EB:5E:65  
              inet addr:192.168.1.44  Bcast:192.168.1.255  Mask:255.255.255.0
              UP BROADCAST MULTICAST  MTU:1500  Metric:1
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

No other network interfaces are active. A ping to localhost works, so I assume everything is OK on TCP/IP level. Why can't I use my ethernet interface?

This question is off-topic for StackOverflow. It should be asked on https://superuser.com/ or https://unix.stackexchange.com/. — Codo, Oct 06 '22 at 12:10
"*I've a custom embedded linux board ...Why can't I use my ethernet interface?*" -- Start testing with an oscilloscope. — sawdust, Oct 06 '22 at 16:47

score 0 · Answer 1 · answered Oct 12 '22 at 19:56

The RUNNING flag is not set, which means that the ethernet adapter doesn't detect a cable inserted.

              UP BROADCAST MULTICAST  MTU:1500  Metric:1
                          ^

This is where the RUNNING flag should be.

You should check your cable assembly for faults, and check if it is plugged in correctly. There may also be a problem with link speed advertising, though nowadays that is very rare.

USB to ethernet: fail to transmit any packages

1 Answers1