Re: Using an old V.92 Haynes modem

[Dan Williams <dcbw redhat com>]

On Tue, 2010-08-10 at 23:45 +0100, Alex Buell wrote:
> On Tue, 2010-08-10 at 14:29 -0500, Dan Williams wrote:
> > On Tue, 2010-08-10 at 17:22 +0100, Alex Buell wrote:
> > > Hi!
> > > 
> > > I think perhaps ModemManager may be misnamed. It can't handle old style
> > > external modems such as my V.92 Haynes modem plugged into serial ports.
> > > But there are situations (for example ADSL goes down) where I would need
> > > to bring up an Internet connection using my V.92 Haynes modem over
> > > dial-up ppp. Is that even possible with NetworkManager? 
> > 
> > Not at the moment; but it's intended to allow ModemManager to handle
> > these modems too.  Unfortunately I get about 30x more requests for
> > mobile broadband stuff than for 56k dialup support...  anybody is
> > welcome to help out with patches; it probably wouldn't even be that hard
> > since most of these modems don't need a ton of initialization, and then
> > you just dial.  What's slightly hard is detecting old-school serial
> > modems connected to platform serial ports.  USB modems should be OK.
> 
> In the next few days I'll be getting a serial to USB cable to plug my
> old V.92 Haynes modem into and see how I get on with that. 
> 
> I also have a P166 with serial port with which I can test. Might be nice
> to have a back-up dial-up Internet for those occasions when broadband
> goes down. 

Yeah, I've thought about it before and actually have a USB modem
somewhere.  It shouldn't be that hard to do.  We might be able to get
away with treating any modem that does not have Mobile Broadband GCAP
(ie, IS707/856 or GSM) and isn't driven by known mobile broadband
drivers as a dialup modem.  After that we figure out what the init
sequence should look like and then we just dial.  It should be a ton
simpler than 3G stuff since there isn't nearly so much to do.

I'd suggest making src/mm-generic-56k.c as the base class and then we
can override that in plugins/ if we find really whacky variants later.

Then in plugins/mm-plugin-generic.c:

1) update get_level_for_capabilities() to return 5 if the port has DS or
ES capability
2) in grab_port() check for CAP_56K (which is (DS || ES) && !CDMA && !
GSM && !QCDM) and make a new modem calling mm_generic_56k_new() which
you wrote in src/mm-generic-56k.c.

that's a start at least.  Actually less work than I thought.

Dan