Gigabit ethernet loopback on i.MX8M eval board

[pnee]

I can't get the 1000Mbps external loopback to work on i.MX8M eval board. The link just never comes up even though I have followed all the suggested steps and have a gigabit external loopback connected.

FYI, the internal gigabit phy loopback, which is almost identical apart from a few lines of code, works fine.

Also, the 10Mbps and 100Mbps external loopback also work with no problem (which is also very similar code apart from one or two bits in different registers).

Is there anything specific to 1000Mbps on i.MX8M? It fells like I am missing something?

The external ethernet loopback is wired as per suggested wiring form the net (4 pairs connected).  

[jamesbone]

Are you using the EVK board?.  If not,  how it is configured the FEC module is  RMII ?  how it is the Ethernet Scenario connection we try from one EVK to another EVK and we were able to get the  speed that you are requesting using a simple PING command.

[pnee]

Yes, this is with the EVK board.

The FEC module is configured to use RGMII.

The test I have uses an external loopback connection wired as per the link below;

https://tikkiweb.net/1997/05/make-your-own-ethernet-loopback-connector/

[jamesbone]

I try the following steps in the EVK board,  in loopback and it is working from my side:

Performing Loopback Testing for Fast Ethernet and Gigabit Ethernet Interfaces - TechLibrary - Junipe... 

What version of the BSP are you using? and  which revision of the EVK board do you have?

[pnee]

The link only shows a 10M/100M loopback (2 pairs). A proper 1000M loopback implements 4 pairs.

I have 10M/100M loopback tests that work just fine. But 1000M loopback test (using 4 pairs) always fails.