Basic (Idiotic) questions about ModemManager / mmcli / libqmi / modems / life

[Thomas Schäfer]

Am Samstag, 13. August 2016, 22:26:43 schrieb Ajay Garg:
> Thanks Thomas.
> 
> On Sat, Aug 13, 2016 at 10:11 PM,  <tschaefer at t-online.de> wrote:
> > Am 13.08.2016 17:28 schrieb Ajay Garg <ajaygargnsit at gmail.com>:
> >> Thanks Thomas.
> >> 
> >> 
> >> Question 2 :
> >> =========
> >> 
> >> Let's take a modem working in QMI-mode.
> >> 
> >> With the "qcserial" and "qmi_wwan" drivers installed, and NO OTHER
> >> VENDOR-SPECIFIC drivers (sierra/zte/huawei/any-other) required or
> >> installed, the modem (after it is inserted in the USB-slot), will have
> >> 
> >> the following two created ::
> >>         * /dev/cdc-... device-identifier
> >>         * a wwan network-interface (visible via "ifconfig" command)
> >> 
> >> Above two will be created, irrespective of whether or not
> >> ModemManager/mmcli is compiled/running with
> >> QMI_DEVICE_OPEN_FLAGS_PROXY set or not.
> >> 
> >> Is my understanding correct?
> > 
> > The creation of the device files is made by the kernel/udev. Sometimes
> > "option" is also loaded, so you have some additional serial ports.
> 
> Question-3
> ============
> 
> Ok, so does this mean that none/one of qcserial/qmi_wwan are required?
> Or both are required to have the wwan-network-interface working properly?

qmi_wwan is a kernel module (part of the kernel). qcserial too. 

But I have only user experience with qmi_wwan. Most of my modem use only 
qmi_wwan.

You need 

Kernel with qmi_wwan --> ModemManager with qmi-support--> NetworkManager-->NM-
GUI

In every layer you can use libs/cli, e.g. qmicli, mmcli, nmcli.

> 
> In other words, if I understand correctly,
> 
>       * /dev/cdc-... would be created, but not by qcserial/qmi_wwan,
> but by udev/kernel.

No. qmi_wwan is part of the kernel. 


>       * wwan network-interface will be created by one or more of
> qcserial/qmi_wwan
>       * qcserial/qmi_wwan are definitely required for function of
> wwan-interface.

yes.

Dear list.
If I am wrong, pleas correct me.


Thomas