Re: problems with 3g based connections

[van Schelve <public van-schelve de>]

>> Hi,
>> 
>> some days ago I have reported a curious issue with modem-manager. 
>> My main Problem is that I'm sometimes not able to dialup a modem based
3g
>> connection. The connection is not listed in nm-applet in this case and
in
>> syslog I have entries like this one: 
>> 
>> ... 
>> May 21 10:055:28 nc0631 modem-manager: (tty/ttyUSB0): outstanding
support
>> task prevents export of /sys/devices/pci0000:00/0000:00:1d.1/usb6/6-1
>> ...
> 
> This means that some ports of the modem are still being detected and
> probed.  The modem cannot be used until all ports have completed
> detection.
> 
>> @Dan, you asked me to bring more debug but I'm not able to reproduce
this
>> issue while manually starting nm / mm in debug mode. 
>> Therefore: is it possible to run network-manager / modem-manager per
>> default in debug mode while starting over upstart?
> 
> Possibly, but the debug output doesn't go to syslog, so unless it gets
> stored somewhere by upstart it'll get lost.

We were able to capture the debug output. Without debug we run 6 of 10
times into
this problem. Running mm in debug mode we were able to reproduce it 3 of
10 times.

http://pastebin.com/RS5vDxwJ
http://pastebin.com/FmZbkJnc
http://pastebin.com/97GPPbZW

> 
>> A second problem, reported by our testorganisation is that existing
>> connections are sometimes terminated. I cannot see the reason for this
>> behaviour.
> 
> Getting logs from modem-manager and from NetworkManager with
> NM_PPP_DEBUG=1 are helpful here:
> 
> http://live.gnome.org/NetworkManager/Debugging
> 
> I'd guess that PPP is terminating for some reason, but we need to figure
> out why that is, and the NM PPP debug logs might help us figure that
> out.  There are a ton of reasons why the call might get terminated, and
> many of them are network side or handoff-related.  Or the firmware
> screws up.  This happens on other platforms too :)
> 
>> And maybe there is a third problem. It looks like that it takes a long
>> time ~6 seconds from powering up the modem until it can be used with
>> network-manager. In the logfiles I see that the different ports are
>> getting
>> probed with all the available plugins. Is there any way to optimize
this
>> behaviour?
> 
> What do you mean by "powering up"?  Just plugging the modem in?

The Lenovo Laptops have a switch to disable / enable the radio devices at
all once.
So it looks like it's like plugging the modem in.

> 
> You might also be forgetting about modeswitching, which takes a few
> seconds (perhaps up to 5 or 7) depending on the device.  Otherwise,
> there might be a few things we can do to eliminate delays, but you'll
> also find that on other platforms things take a while to initialize too.
> That doesn't mean we can't do better than we do right now, but there
> will always be some amount of delay as the device is modeswitched,
> detected, and initialized.

Ok, I understand. I will do some measurings to determinate how long it
took with our 
old wvdial script and the new nm / mm implementation.

> 
> Getting the ModemManager debug logs help here.

Here it is:

http://pastebin.com/jLGNrjNq

> 
> Note that some devices (Airlink 3GU and other Longcheer-based modems)
> have kernel driver problems that delay their detection by up to 30 or
> more seconds.
> 
> Dan