Sierra Wireless MC7354: Why all the interfaces?

Aleksander Morgado aleksander at
Mon Oct 23 15:46:39 UTC 2017


>>>>> So some basic questions:
>>>>> 1) Why multiple interfaces? What do they mean? Are they different
>>>>> bands (3G/LTE/etc)? Where can I read up on this?
>>>> You're probably using an old kernel as well, because the 3rd interface
>>>> (wwan2) shouldn't be exposed. I removed it from qmi_wwan a while ago
>>>> because it was non-functional.
>>> It's ancient (3.x). We don't even have raw IP support in qmi_wwan.  I
>>> really would like to get to 4.9.
>>> We were also considering Sierra Wireless MC7455, but that's Raw IP
>>> only so it didn't register in ModemManager after I patched qmi_wwan to
>>> add it.
>> What do you mean that it didn't register with ModemManager after
>> patching qmi_wwan? Maybe you didn't port all commits you needed? I
>> believe there was some usbnet driver change that would also have been
>> required.
> It's not really important, but I mean:
> I only added a couple of patches to drivers/net/usb/qmi_wwan.c from
> Bjørn Mork to identify MC74xx for qmi_wwan.
> The end result was:
> +       {QMI_FIXED_INTF(0x1199, 0x9071, 8)},    /* Sierra Wireless MC74xx */
> +       {QMI_FIXED_INTF(0x1199, 0x9071, 10)},   /* Sierra Wireless MC74xx */
> +       {QMI_FIXED_INTF(0x1199, 0x9079, 8)},    /* Sierra Wireless EM74xx */
> +       {QMI_FIXED_INTF(0x1199, 0x9079, 10)},   /* Sierra Wireless EM74xx */
> The 0x9071 lines created wwan0 + wwan1 interfaces for MC7455, but
> ModemMonitor couldn't initialize the cdc-wdm[01] ports so mmcli -L
> found nothing. See syslog below (no debug info).
> I did not attempt to add his patches "net: qmi_wwan: support "raw IP"
> mode" and "usbnet: allow mini-drivers to consume L2 headers".
> I'm not really concerned about that at this time, since I am thousands
> of patches behind in my kernel and probably need many other things to
> get MC7455 to work on this setup, while MC7354 (almost) works out of
> the box.

Probably with those two other patches that you just listed you would
have had MC7455 support in your kernel :)


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