Fibocom L850-GL / Intel XMM7360

[Wassenberg, Dennis]

Hi all,

we get our first Lenovo 2020 series Thinkpad models and would like to make WWAN/LTE working.
The devices of this year support 2 different WWAN/LTE modems:

a) CAT9 Fibocom L850-GL / Intel XMM7360
b) CAT16 Fibocom L860-GL

That applies at least to all T- and X- series Thinkpads. So there is no option to have a pure USB based LTE modem
inside.

We focused on the Fibocom L850-GL / Intel XMM7360 because this modem has the option to switch into usb mode.

Whats the most practical way to support the Fibocom L850-GL / Intel XMM7360 modem?
As far as I know there are two main directions:

1) Switch the modem into usb mode

I used this https://github.com/xmm7360/xmm7360-usb-modeswitch to switch the modem to usb mode. Unfortunately this seems
not to work completely. After disabling the PCIe link I can notice the device at the usb bus but after round about 7
seconds it will disappear from the usb bus.

So, the script said:

Found XMM7360 modem at 0000:2c:00.0 (\_SB_.PCI0.RP07.PXSX)
Parent port is at 0000:00:1c.6
Disabling PCIe link...
OK!

After that dmesg shows this:
[ 930.843781] usb 1-7: new high-speed USB device number 16 using xhci_hcd
[ 930.996572] usb 1-7: New USB device found, idVendor=8087, idProduct=07f5, bcdDevice= 0.00
[ 930.996577] usb 1-7: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 937.683939] usb 1-7: USB disconnect, device number 16

So, in general I think there should be USB lines routed to the M.2 slot but I have no idea why the device leaves the
bus. It is possible to run the script again and again but in the end it will always disconnect automatically.

That means it is not possible to issue the AT commands to switch to MBIM mode.

Does anybody has a hint how to make further investigations on this?


2) Use the PCIe based driver

I read this https://github.com/xmm7360/xmm7360-pci but I currently didn't try it.

I would like to know how is the current situation from ModemManager perspective. Will the ModemManager work together
with the pcie driver or is it in development/planned?


So, in conclusion: Whats the best solution to support this modem? Would it be better to use the USB mode or should we
use the PCIe mode instead?

If somebody has ideas or hint to make this modem work, please tell me :)

Thank you & best regards,

Dennis