qmi_wwan add_mux/del_mux

[Daniele Palmas]

Il giorno gio 21 gen 2021 alle ore 17:52 Aleksander Morgado
<aleksander at aleksander.es> ha scritto:
>
> Hey again,
>
> > Say I create a new muxed interface for mux id 5:
> >   echo 5 > /sys/class/net/wwan0/qmi/add_mux
> > A new qmimux0 interface is created.
> >
> > Is there any way to know which mux id was used to create the qmimux0
> > looking just at sysfs or some other way? In other words, how would I
> > know what the mux id is for a given qmimuxN interface that may not
> > have been created by me?
> >
> > Also, say that I have 2 different programs creating this kind of
> > interfaces, and both use the qmi/add_mux attribute. If they both run
> > at the same time (asking for different mux ids), and two interfaces
> > qmimux0 and qmimux1 are created, how can each program know which was
> > the interface corresponding to the mux id they requested?
> >
> > Not sure I'm missing something, but I didn't find a way to do this
> > kind of matchings. If the virtual qmimux interface exposed a sysfs
> > attribute specifying which is the mux id they correspond to, the
> > matching would be much easier. Would that be possible?
> >
> > For context, I'm trying to work on adding support for this interface
> > in libqmi, with the new qmi_device_add_link() interface that is right
> > now only available when using rmnet with netlink.
> >
>
> In the context of multiplexing QMUX data sessions, Stephan also
> suggested we revive this old patch that never got a v2 in the LKML:
> https://lore.kernel.org/netdev/1530066614-24995-1-git-send-email-subashab@codeaurora.org/
>
> Adding support to use rmnet on top of qmi_wwan seems like a good idea,
> and we would be able to use the implementation we already have for
> e.g. IPA, e.g.:
> https://gitlab.freedesktop.org/mobile-broadband/libqmi/-/merge_requests/184#note_715900
>
> What do you all think?

I think that would be the best solution, since it also allows
homogeneity with PCIe MHI.

Reading again the comments, it seems to me that the patch was not too
far to be acceptable, so maybe it would be worth looking at it again.

Regards,
Daniele

> --
> Aleksander
> https://aleksander.es