Failed to find primary AT port (Jan Graczyk)

[Einar Jón]

>
> Hello Dan,
>
> Thank you for your response. The next question I have for you is how to cross compile ModemManager for ARM architecture. I am using ModemManager version 1.4.2 to build. Is that version stable enough to run on ARM based processor? The version of ModemManager on my target is 1.4.0 and it is working well.
>

What environment are you using? I use buildroot, and building
ModemManager as a packace there is really straightforward. I can also
confirm that qmi_wwan can work, like Dan says.

>
> On Fri, 2017-03-31 at 21:09 +0000, Jan Graczyk wrote:
>> Hello Dan,
>>
>> There is no problem with connecting to this modem (mini PCIe Quectel
>> UC20 modem module) from kermit and sending AT commands. However when I
>> issue the following commands:
>>
>>  mmcli -m 0 --simple-disconnect
>>  mmcli -m 0 --simple-connect="pin=1234,apn=internet"

What's your kernel version?
Note that you may need to compile in some extra features from Quectel
in order to get everything to work. A simple way to check is "ls
/dev/ttyUSB*", which should return 4 devices (ttyUSB0 to ttyUSB3).
If that's missing, you might want to add the extra source lines in
this document:
http://support.lyconsys.com/download/3gplus5/Android/USB/Quectel_WCDMA&LTE_Linux_USB_Driver_User_Guide_V1.4_Preliminary_20151103.pdf

Or just update your kernel to a newer version (kernel 4.4 seems to
have all the Quectel additions). Without the Quectel additions and the
tty ports the modem is really fragile, and the smallest error can make
it lose connection until the next modem restart (by rebooting the
device or sending an AT+QRST=1,0 command to ttyUSB2 or ttyUSB3).

When installed, you should see a bunch of ttyUSB ports in the System
section of mmcli -m 0:
  System   |         device:
'/sys/devices/pci0000:00/0000:00:17.0/0000:01:00.0/0000:02:08.3/usb2/2-3'
           |        drivers: 'qmi_wwan, option1'
           |         plugin: 'Generic'
           |   primary port: 'cdc-wdm0'
           |          ports: 'ttyUSB0 (qcdm), ttyUSB2 (at), ttyUSB3
(at), wwan0 (net), cdc-wdm0 (qmi)'

Good luck
Einar Jón