Aha! Based on this, I plugged it into the 4x10 port on the 6610 and it's working perfectly, albeit at 10g instead of the desired 40. Let's be honest though, I'm not likely not see any real world difference any time soon, as 10g should even saturate my zfs NAS.
I'd love to be able to flash new firmware, but I can't figure out how to force it to do so. All of the mellanox utils seem to reject it due to the odd PSID.
Awesome, I'm glad you got it working.
fohdeesha mentioned that when he connected the 40G-LR4 transceivers to the QSFP breakout ports between two ICX6610 switches, it showed all four lanes in use. I didn't realize it would work when connecting to a client that only supports a single 10G lane.
However, the downside of using the QSFP breakout port with a 40G-LR transceiver for a single 10G lane is additional power and heat at the client and switch, as well as the loss of 3 out of the 4 brekaout ports. The dual port 40G Mellanox NICs use 8-9W whereas a single 10G Mellanox NIC ( CONNECTX-3 EN CX311A) uses around ~3.3W and the dual uses 4.44W. I find the CX311A great for enabling 10G connectivity on desktop machines. It's tiny, low power, can be purchased with a short or long bracket for around $25, and works with SFF machines as long as there's a x4 PCI-E slot.
The 40G-LR4 Lite transceiver uses ~2.5W and gets reasonably warm (~48-50C) whereas the 10G-LR and 10G-SR transceivers use 1W or less and run near ambient temp (30-32C). If you only need 10G, you can use a 10G-LR SFP+ transceiver with the existing SMF cable ($5 on Ebay if you don't care about digital optical monitoring). I was able to purchase a lot of 4 genuine Brocade 10G-LR4 transceivers for $20, but I don't see any cheap ones at the moment. If you run OM3, you can use $5 original Brocade 10G-SR transceivers and get digital optical monitoring.
If instead you want working 40G, and your current card can't be flashed, many folks here can confirm that the HP 649281-B21 can be flashed easily using the above instructions. I've already done two cards myself, and they only cost $30. Unlike the CX311A NICs, these have working digital optical monitoring, and it seems to work with any manufacturer, since it works with the KAIAM transceivers with detailed info.
I'm basically using all of the above options for different needs, as well as a FS 40G to 4 x 10G SFP+ breakout DAC for my pfsense router.
SSH@ICX6610-48p> show media validation
1/2/1 Yes KAIAM CORP 40G QSFP Module
1/2/2 Yes BROCADE 40GBASE-Passive Copper
1/2/3 Yes BROCADE 40GBASE-Passive Copper
1/2/4 Yes BROCADE 40GBASE-Passive Copper
1/2/5 Yes BROCADE 40GBASE-Passive Copper
1/2/6 Yes KAIAM CORP 40G QSFP Module
1/3/1 Yes BROCADE Type : 10GE SR 300m (SFP +)
1/3/2 Yes BROCADE Type : 10GE SR 300m (SFP +)
1/3/3 Yes BROCADE Type : 10GE LR 10km (SFP +)
1/3/4 Yes BROCADE Type : 10GE SR 300m (SFP +)
1/3/5 Yes BROCADE Type : 10GE LR 10km (SFP +)
1/3/7 Yes BROCADE Type : 10GE LR 10km (SFP +)