Netgear Aircard 341U in QMI mode, switching to 802.3

[Bjørn Mork]

Markus Gothe <nietzsche at lysator.liu.se> writes:

> Well, I dare you on this.
> Go show me a PoC and I’ll consider it.

It's possible, but I agree that it quickly will become ugly.

I tried something like this for MBIM IP session IDs while experimenting
with different ways to solve the MBIM multiplexing.  As you know now, I
ended up dropping all that. Instead userspace have to syncronize netdev
creation with MBIM session creation.  I'm still not sure which solution
is best/worst.  Both have their advantages and disadvantages.  But I
know why I selected the one I did:  It was the simplest one for me :)

Do note though, that there aren't yet any userspace implementation of
the MBIM multiplexed sessions (AFAIK).  Adding some userspace PoC for
this has been on my TODO list for quite a while, but is still not done.
That's also a factor to consider here.

> What I’ve in mind is this:
> http://www.spinics.net/lists/linux-usb/msg58432.html where Björn
> showed us off...

Which has the disadvantage that it adds yet another userspace API, with
strict rules on how it should interact with the existing API, while
offloading all the policing to userspace.  Not nice.

The userspace QMI offloading was a success, but if we go too far in that
direction then we risk making it impossible to create userspace tools.
Having a single well-defined management protocol managed by userspace is
fine.  Combining it with rules on how to configure the netdev is not.
(Which means that the qmi_wwan driver ideally should do the MTU setup
for example.  But it doesn't.)

I tend to agree with Dan on the raw-ip issue.  Snooping on the device
setup in the driver will allow all existing QMI userspace
implementations to use raw-ip without any major changes.

But I do still hope we can avoid doing the raw-ip support at all.


(I have a nasty feeling that we compete with the firmware setup here,
and that the reason the 802.3 commands fail is that there is some
firmware application needing the modem in raw-ip mode.  We risk that new
firmware revisions will try even harder...)


Bjørn