Issue observed on Huawei ME936 since commit 0c7f3380a

[Ben Chan]

I've been debugging an issue with Huawei ME936 (in MBIM mode). The issue is
observed since commit 0c7f3380a ("bearer-mbim: ensure session is
disconnected before trying to connect").

>From what I observe, the first connection attempt on ME936 always times out
when MMBearerMbim issues a MBIM_CID_CONNECT
(MBIMActivationCommandDeactivate) command to force deactivating a session
that hasn't yet been activated. But as MMBearerMbim currently ignores that
error, it proceeds to issue MBIM_CID_CONNECT
(MBIMActivationCommandActivate) command, which then also fails. For some
unknown reason (mostly like a firmware bug), the modem takes more than 30s
(i.e. the current timeout) to deactivate a session that hasn't been
activated once.

Increasing the timeout would address the issue, but I'm not too happy to
wait 30-40s for a unnecessary operation. So I thought I could query the
activation state of the session before trying to deactivate it.
Unfortunately, the modem always reports a "unknown" activation state if the
session hasn't been activated once (well, most likely yet another firmware
bug).

As the chance of getting a firmware fix seems slim, I try to address that
in ModemManger / libmbim with the following patches:

---

modemmanager-devel:
https://lists.freedesktop.org/archives/modemmanager-devel/2018-February/006167.html
https://lists.freedesktop.org/archives/modemmanager-devel/2018-February/006165.html
https://lists.freedesktop.org/archives/modemmanager-devel/2018-February/006166.html

libmbim-devel:
https://lists.freedesktop.org/archives/libmbim-devel/2018-February/000985.html
https://lists.freedesktop.org/archives/libmbim-devel/2018-February/000986.html

---

Thanks,
Ben
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