qmi_wwan add_mux/del_mux

[subashab at codeaurora.org]

On 2021-01-22 03:00, Aleksander Morgado wrote:
> Hey,
> 
> I've added Subash in CC of the thread.
> 
> On Thu, Jan 21, 2021 at 11:23 PM Daniele Palmas <dnlplm at gmail.com> 
> wrote:
>> 
>> 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.
>> 
> 
> Subash, any reason why the patch was forgotten and no v2 proposed? Is
> there something we can do to push it forward?

Hi

That was my bad. I will send an updated patch with the changes mentioned
by Bjørn.