ANN: ModemManager 1.18.4 released / Avoiding PPP

[Dan Williams]

On Fri, 2022-01-14 at 16:29 +0100, Aleksander Morgado wrote:
> Hey Peter,
> 
> On Fri, Jan 14, 2022 at 4:14 PM Peter Naulls <peter at chocky.org>
> wrote:
> > 
> > On 1/14/22 10:09 AM, Aleksander Morgado wrote:
> > logic is not going to change.
> > > 
> > > If MM detects a single TTY port, it's going to default to use
> > > PPP.
> > > It's not a fallback to PPP, it's using whatever it has for data
> > > connection, if PPP is the only way forward, PPP will be.
> > 
> > I don't want PPP, ever.  I don't know how many times I can repeat
> > that.  Please stop saying this and arguing with me about it.
> > 
> 
> I know you don't want PPP in your setup, you have made that clear.
> I'm
> not arguing with you about that. I get it. You don't want PPP.

Yeah, MM has to work for a lot of people, some who want PPP and many
who don't. But there's still enough PPP going around that it must
continue to be supported for a while.

> 
> Now, the way to fix that should be by making sure ModemManager gets
> notified of the QMI/NET port before it creates a modem object only
> with TTY ports. I understand that you don't like this approach, but
> ModemManager doesn't receive a fixed list of ports to work with, as
> many other modem management setups. MM tries to dynamically adjust to
> what it finds, and that is a core feature of ModemManager that is not
> going to change.

In the past IIRC we've seen bad udev rules or scripts taking multiple
seconds to evaluate or do something (I think usb_modeswitch was a
problem here once upon a time) and delaying updates for specific ports
of a device. Not sure if that's a problem here, or if the system is
just slow.

> 
> So again, and don't hate me for repeating this, if MM gets notified
> of
> one single AT capable TTY port and nothing else, it will default to
> use PPP. If you don't like that, please patch your ModemManager to
> fit
> your needs. Or try moving to uqmi, which requires you to specify
> which
> is the cdc-wdm port path explicitly, although that approach has its
> own problems, but maybe not the ones you're worried about.

I haven't read the whole thread in detail, so forgive me if this was
covered. Perhaps a way of tagging a modem/driver/whatever with "never
use PPP" would be workable. Off by default of course.

Dan