On Mon, 2021-02-01 at 19:27 +0100, Loic Poulain wrote:

On Mon, 1 Feb 2021 at 19:17, Dan Williams [off-list ref] wrote:

quoted

On Fri, 2021-01-29 at 18:21 -0800, Jakub Kicinski wrote:

quoted

On Wed, 27 Jan 2021 18:01:17 +0100 Loic Poulain wrote:

quoted

MBIM has initially been specified by USB-IF for transporting
data
(IP)
between a modem and a host over USB. However some modern modems
also
support MBIM over PCIe (via MHI). In the same way as
QMAP(rmnet),
it
allows to aggregate IP packets and to perform context
multiplexing.

This change adds minimal MBIM support to MHI, allowing to
support
MBIM
only modems. MBIM being based on USB NCM, it reuses some
helpers
from
the USB stack, but the cdc-mbim driver is too USB coupled to be
reused.

At some point it would be interesting to move on a factorized
solution,
having a generic MBIM network lib or dedicated MBIM netlink
virtual
interface support.

What would a kernel-side MBIM netlink interface do?  Just data-
plane
stuff (like channel setup to create new netdevs), or are you
thinking
about control-plane stuff like APN definition, radio scans, etc?

Just the data-plane (mbim encoding/decoding/muxing).

Ah yes :) If so, then fully agree.

But is that really specific to MBIM? eg, same kinds of things happen
for QMI. Johannes referred to a more generic WWAN framework that we had
discussed 1.5+ years ago to address these issues. Might be worth
restarting that, perhaps simplifying, and figuring out the minimal set
of generic bits needed to describe/add/delete a data channel for WWAN
control protocols.
Dan