Loopback in Ethernet PHY

Is it possible to test Ethernet physical layer with SmatBits by configuring JTX2 to loopback mode?
If yes, how to do it?

Thanks.

tx2 loopback mode?
like what?
you can use 127.0.0.1 for the loopback

I think he wants to test the actual physical layer…loopback via 127.0.0.1 won’t go through the PHY (and in fact 127.0.0.x exists for systems without access to an outside network). It might be easier to answer with details…I’ve not heard of that software.

Physical layer like if wires pass logical 0 or 1? Or like if there are at wires whatever 5v or whatever values ?

something like below?
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/ethernet-fast-and-gigabit-loopback-testing.html
what is SmartBits?
According to the article https://en.wikipedia.org/wiki/PHY_(chip), Ethernet PHY refers to the physical level of the model OSI.
some links:
https://devtalk.nvidia.com/default/topic/1026982/jetson-tx2/tx2-ethernet-phy-questions/
https://devtalk.nvidia.com/default/topic/1009965/ethernet-phy-ic-datasheet-of-jetson-tx1/?offset=1
https://devtalk.nvidia.com/default/topic/1028457/advice-for-connecting-multiple-tx2-modules-on-a-single-pcb-via-gigabit-ethernet/
https://stackoverflow.com/questions/8071953/coding-for-ethernet-phy-loopback-test
The below is the attached BCM89610 Product Brief. As far as I am concerned, BCM89610 is what is used at tx2 and that includes the PHY.
89610-PB00-R.pdf (282 KB)

Linuxdev is right I like to test the actual layer by enabling the ethernet phy of JTX2 to activate a loopback mode.

Perhaps you are looking for something like https://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/p/377771/1341503

I can see why you might want to make it talk to itself for testing, but since ethernet is bidirectional it might be an issue. If for example a bridge is configured to have it talk to itself the system will crash (it wouldn’t be a bug of the bridge, though it isn’t what I’d call a graceful way to fail). Perhaps forcing half duplex could get around having external hardware, but I kind of doubt it (if you dual home and you have it half duplex it might work…but unfortunately I think the network software is smart enough to know the interface is talking to itself and wouldn’t actually route it through the PHY). Maybe you could build a custom driver which is a modified Realtek driver.

An external network analyzer tool would be the way to go (sorry, I don’t know of an inexpensive way to do this).

Let me check if there is anything I can help. I’ll reply once finding something.

I don’t know what PHY test you want to conduct.

Actually, we indeed have some loopback test for bringing up tx2 ethernet long time ago, but unfortunately I cannot share it with public.

Please contact Broadcom if you need such tools.

Do you have a more specific address at Broadcom?