Some questions about qmi/wwan

[E:V:A]

These are surely some interesting questions.

> On Fri, 2014-07-25 at 19:17 +0200, Marco wrote:
>> - Once the kernel module is loaded, I get two /dev/cdc-wdm devices (0 and
>> 1). What are those for? The one that seems to be working with qmicli is
>> /dev/cdc-wdm1. I also get two network interfaces, wwp0s20u6 and
>> wwp0s20u6i3, the second one is the one that I can use dhcp client with and
>> get an IP. Which is the purpose of the other one?
>
> I'll leave that to Bjorn and Aleksander, but on some devices there is a
> second non-operative QMI configuration.  Could be a firmware quirk.
>

Hmm, I'm not sure that's it. On most Qulacomm modems, there are a
(large) number of "debug" interfaces that can be enumerated. However,
it is far from clear what they all do and how to use them. We know
this from studying the Gobi phone equivalents of the Snapdragon S4
family (that include MSM8960 etc.) For example different intefaces are
(often) used for GPS, Emergency Download Mode (firmware updates etc)
and RF debug output that is used by proprietary software like QPST and
QXDM. These often appears as sockets on and inside Androids. But as
separate USB devices on the outside. So any additional information
that can shed some light on what these devies do, would be very
welcome.

>> - The device has an integrated GPS (PDS in qmi-speak). I understand that,
>> currently, with libqmi it is not possible to use it (or at least I see no
>> pds-* options in qmicli 1.10.0, which is the version I'm using). Is that
>> right?
>
> qmicli doesn't have support for that, but programs like ModemManager use
> libqmi to provide it.

What would it take to implement this? What is needed?