[FS#641] Quectel ECXX and Raw IP on 4.4 kernel

[LEDE Bugs]

The following task has a new comment added:

FS#641 - Quectel ECXX and Raw IP on 4.4 kernel
User who did this - wildy (wildy)

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Hi. 

We've got a couple of ar71xx devices (GL-inet MIFI) that are shipping with the new Quectel EC25 modems. I have quickly grown tired of using them in PPP mode so I tried to backport qmi_wwan.c from upstream 4.9 into 4.4 (LEDE 17.01.2).
As of now, uqmi works but I can't seem to obtain a DHCP address on wwan0, both in Raw IP mode and 802.3 mode.

See: https://github.com/wildy/LEDE-source/commit/bde7af1789bf42ad1483150834ba94827350ca6e

I think that might be caused by some changes in usbnet code that we need to backport too?

I will try to make a more clean backport involving only the commits needed for EC25 but for now it would be nice to see if it works at all :)
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=641#comment2864