Adding new mbimcli option to open/close DSS channels?

Bjørn Mork bjorn at
Mon Feb 24 04:28:56 PST 2014

Scott Lee <sclee at> writes:

> We're working on our LTE modem to support MBIM interface.
> We need to open DSS channels and we find there's "mbim_message_dss_connect_set_new" function in "mbim-dss.c".
> However it's not available in any mbimcli options.
> Would you please suggest whether it's under developing, or we could submit a patch for it?
> If we could do it, is it good to add a new group "dss" or we should add it into existing group such as "basic-connect"?

I cannot answer those questions, but I am really interested in any
feedback and/or information regarding DSS usage. The driver support was
added without much knowledge of actual usage, and without much testing
on real firmware implementations.  So it's rather unpolished, and mostly
untested AFAIK...

What kind of DSS service(s) does this device support?  What is the
preferred kernel<->userspace interface for this service (tty, netdev,
other?).  Are you able to work with the current pseudo VLAN
encapsulation of the data channel?

FWIW, the firmware I tested it on exports an AT command channel which is
best used as a tty from userspace.  So what I did to use DSS session #0 was

      ip link add link wwan0 name wwan0.256 type vlan id 256
      ip link set dev wwan0.256 up
      socat INTERFACE:wwan0.256,type=2 PTY:,echo=0,link=/tmp/modem

using /tmp/modem as if it was a normal tty device.


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