MM: Non QMI Huawei modems without PPP support?

[Bjørn Mork <bjorn mork no>]

Hello,

following up the recent discussions on libqmi regarding E3276 I am
wondering if these modems could be supported without too much fuzz by
ModemManager?

This is a typical example of such a device (after adding the necessary
match to the cdc_ncm driver):

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=12d1 ProdID=1506 Rev= 1.02
S:  Manufacturer=HUAWEI Technology
S:  Product=HUAWEI Mobile
C:* #Ifs= 4 Cfg#= 1 Atr=80 MxPwr=500mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=02 Prot=12 Driver=option
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms
I:  If#= 1 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=02 Prot=16 Driver=cdc_ncm
E:  Ad=82(I) Atr=03(Int.) MxPS=  64 Ivl=2ms
I:* If#= 1 Alt= 1 #EPs= 3 Cls=ff(vend.) Sub=02 Prot=16 Driver=cdc_ncm
E:  Ad=82(I) Atr=03(Int.) MxPS=  64 Ivl=2ms
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=4ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms


So, except for the Mass Storage functions, there is only one serial
function and one CDC NCM function available.  And according to the
Windows drvier inf, the serial function is intended for PCUI.  It is
used to manage the CDC NCM function, and may not support PPP at all(?)

Ideally ModemManager should use the wwanX interface for data and the
ttyUSBY device for control, using Huawei vendor specific AT commands to
initiate and manage the connection.  The known commands specific to
network device management are AFAIK

connect:
AT^NDISDUP=1,1,"apn"

disconnect:
AT^NDISDUP=1,0

check:
AT^DHCP?

The last command will return all addresses, but the firmware also
support running DHCP over the network interface so using these is not
necessary .  The command is still useful to check whether there is an
active connection or not.

Is this something which can be supported relatively easy?

I do not know how common these devices are, but the E3276 is relatively
new so there might be an increasing demand for this. Based on the
Windows driver I expect there are also similar devices with a CDC ECM
function instead of NCM, but I have not seen any example of those yet.
So I have so far only submitted a patch for cdc_ncm.



Bjørn