Unable to Force Link Speed for ConnectX-4 Lx on Windows

I’m troubleshooting a ConnectX-4 Lx stuck at 1Gbps on a machine that was previously running fine at 40Gbps with ConnectX-3.

I can’t seem to manually set the link speed:

>Mlx5Cmd.exe -LinkSpeed -Name "Ethernet 2" -Query
Link is down
Couldn't query the linkspeeds supported by cable since the link is down

LinkSpeeds supported by device only:
1 Gbps
10 Gbps
25 Gbps
40 Gbps

>Mlx5Cmd.exe -LinkSpeed -Name "Ethernet 2" -Set 1
ERROR: set command is not supported.

>Mlx5Cmd.exe -LinkSpeed -Name "Ethernet 2" -Set 10
ERROR: set command is not supported.

>Mlx5Cmd.exe -LinkSpeed -Name "Ethernet 2" -Set 25
ERROR: set command is not supported.

>Mlx5Cmd.exe -LinkSpeed -Name "Ethernet 2" -Set 40
ERROR: set command is not supported.

How do I get this to work? Thanks!

Adapter info:

Driver Version : 3.10.25798.0
Firmware Version : 14.32.1010
Port Number : 1
Bus Type : PCI-E 8.0 GT/s x4
Link Speed : ----
Part Number : MCX4131A-BCAT
Device Id : 4117
Revision Id : 0
Network Status : Disconnected
Adapter Friendly Name : Ethernet 2
Port Type : ETH

Why are you trying to force a link speed?

Our HCA(s) by default is set to auto-negotiate (It should be a plug and play)

What is the switch that HCA/port connects to?

Is the setting on that switch port to AN or no AN (Aka force speed)?

Are you using a supported cable for the CX4 LX based on the supported speed of that HCA?

Is the main goal to bring the link up or determine why mlx5cmd.exe LinkSpeed/Set not working?

I don’t have a Windows lab setup handy though I would suggest opening a support case should it needs to be investigated further.

Also, comparing CX3 & CX4 LX is not a good comparison, two different beast…

I previously had two ConnectX-3 MCX354A’s using Kaiam XQX2502’s directly connected together at 40Gbps. There is no switch involved.

When I upgraded the machine to Alder Lake, the ConnectX-3 Windows drivers would BSOD when the E-cores were active.

Swapping a ConnectX-4 MCX4131A-BCAT in fixed the BSOD, but failed to connect at 40Gbps with the same equipment.

I wanted to set the card explicitly to 40Gbps to see if that would fix the issue. Is there a known issue with setting the link speed?