Using Sierra MC7304 LTE modem with QMI

Question

I am using a Sierra MC7304 LTE modem on my ALIX-Board with Ubuntu. As far as I understand there are two ways to use it:

• creating a ppp connection via /dev/ttyUSB2 using e.g. wvdial (not suitable for LTE because of the serial interface limitations)
• connecting via qmi

Currently the modem is using GobiNet/GobiSerial drivers that create /dev/ttyUSB0-2 devices that work with wvdial.

usb-devices
T:  Bus=01 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1199 ProdID=68c0 Rev=00.06
S:  Manufacturer=Sierra Wireless, Incorporated
S:  Product=MC7304
C:  #Ifs= 6 Cfg#= 1 Atr=e0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=GobiSerial
/usr/bin/usb-devices: line 79: printf: a: invalid number
I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=GobiNet
/usr/bin/usb-devices: line 79: printf: b: invalid number
I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I:  If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=GobiSerial
I:  If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=GobiSerial
I:  If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=GobiNet

My intention is to connect using qmi to achieve better data rates.

For this, I have loaded qmi_wwan via modprobe. My understanding is that loading this module should create a device /dev/cdc-wdm that can be used to connect via qmi. However, no such device appears. Removing the GobiNet/GobiSerial modules via rmmod only leaves the modem without any drivers at all.

Can someone please tell me how I can use MC7304 with qmi? Thanks!

Answer 1

You need to remove the GobiNet driver before loading qmi_wwan for the probing to work. The devices will be named /dev/cdc-wdm0 and /dev/cdc-wdm1.