tomvit
Posts: 2
Joined: Sun Sep 09, 2018 3:07 pm

PoE HAT - eth0 not working

Sun Sep 09, 2018 3:37 pm

Hi all,
I have just purchased PoE HAT together with RPI 3 Model B+ but cannot make eth0 working. The below is the summary of what I did and tried:

- Only power with PoE HAT works fine, RPI is working fine (no sudden restarts or anything like that), just eth0 link does not work.

- when I start up RPI and check dmesg for any eth0 issues, I can see the only eth0 message after start up:

[ 17.710749] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready

- smsc95xx seems to work fine, I see the below in dmesg as well as ifconfig shows eth0 and MAC address but no IP address:

[ 0.280147] usbcore: registered new interface driver smsc95xx

eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
ether b8:27:eb:5b:75:39 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

- The two ethernet LEDs (green and yellow) are off.

- The fan works as normal, turning on and off as per the temperature I suppose.

- I updated RPI to the latest version by running but did not help at all.

apt-get update && apt-get dist-upgrade -y

- I am using passive PoE injector, should be compatible with 802.3 af. It powers other two devices in my network without issues, one being older rasberry pi with external PoE splitter.

- Wifi works as normal.

- When I detach PoE HAT and power RPI with USB power cable, all works including eth0 (with yellow LED blinking), can get IP address via DHCP without issues.

I suspect that this is PoE HAT hardware issue and need to get a replacement but first wanted to check here if I am still missing something.

Thanks,
Tomas

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: PoE HAT - eth0 not working

Sun Sep 09, 2018 5:09 pm

If you have log messages about smsc95xx then you do NOT have a 3B+. The smsc95xx is the 10/100 chip used on all boards prior to the 3B+. The 3B+ uses the lan78xx driver.
Do you have the extra 4 pins (2x2) beside the 40 pin GPIO header that the PoE HAT uses to pick up the ethernet power taps? If not then you definitely have the wrong board.
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drgeoff
Posts: 8491
Joined: Wed Jan 25, 2012 6:39 pm

Re: PoE HAT - eth0 not working

Sun Sep 09, 2018 6:26 pm

6by9 wrote:
Sun Sep 09, 2018 5:09 pm
If you have log messages about smsc95xx then you do NOT have a 3B+. The smsc95xx is the 10/100 chip used on all boards prior to the 3B+. The 3B+ uses the lan78xx driver.
Do you have the extra 4 pins (2x2) beside the 40 pin GPIO header that the PoE HAT uses to pick up the ethernet power taps? If not then you definitely have the wrong board.
The OP wrote " Only power with PoE HAT works fine, RPI is working fine ". No model RPI other than a 3B+ could power up from POE into an official POE HAT.

But why the smsc95xx in "[ 0.280147] usbcore: registered new interface driver smsc95xx" ?

tomvit
Posts: 2
Joined: Sun Sep 09, 2018 3:07 pm

Re: PoE HAT - eth0 not working

Sun Sep 09, 2018 8:05 pm

Yes, this should be Model B+ with extra 4 pins besides GPIO that I use to insert PoE HAT.

Also checked lan78xx and it is in dmesg too but apparently smsc95xx is from some reason in there too.

[ 0.279930] usbcore: registered new interface driver lan78xx
[ 3.307378] libphy: lan78xx-mdiobus: probed
...
[ 0.280147] usbcore: registered new interface driver smsc95xx

Can you guys please check the dmesg.out [1] if you spot anything that could cause this issue?

Thanks,
Tomas

[1] http://vitvar.com/misc/dmesg.out

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