mbim-proxy listening to systemd suspend/resume events

Bjørn Mork bjorn at mork.no
Sun Sep 13 08:56:18 UTC 2020


Aleksander Morgado <aleksander at aleksander.es> writes:

> This is something that could obviously be fixed in the side of the
> device, but it is also something we can avoid in the host side, by
> making sure all MBIM sessions between host and device are brought down
> on suspend, and brought up again automatically on resume.

Won't that disconnect all IP sessions as a side effect?  I can imagine
use cases where that's unwanted.

IMHO, the host should (and do) suspend the USB bus, but not touch any
higher level stuff unless explicitly configured to do so.  This will
allow a powered modem to maintain active connections, so that the host
can resume them when it wakes up.

Killing connections on suspend and reconnecting on resume is sub-optimal
behaviour.  It breaks all established tcp sessions unless you have a
static address.  Completely unnecessary.

I hate all sort of "bring down networking" on suspend.  It just makes
suspend pointless.  You might as well power off then.

Maybe the mbim-proxy open/close logic could follow client activity to
support forcing a session to close?  I.e open it on first client open,
and close on last client close.


Bjørn


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