Re: Environment woes

[Josua Dietze <digidietze@draisberghof.de>]

Am 10.08.2010 21:30, schrieb Greg KH:

> On Tue, Aug 10, 2010 at 12:37:23AM +0200, Josua Dietze wrote:
>> I maintain a Linux tool to put USB devices from one mode (or state)
>> to the other.
>
> What program, usb-modeswitch?


That's the one, yes.

>> Usually there is more than one interface exposed after the mode
>> switch, but only one is suitable for a wireless connection; binding
>> the GSM driver ("option") or the generic serial driver will add
>> multiple ports though (ttyUSB).
>
> Let the modem-manager program handle knowing which tty device to use,
> that type of logic can usually only be detected after talking to the
> device.


Unfortunately, I keep receiving reports that modem-manager picks the 
wrong port after probing, and there is no way of setting the port 
manually in NetworkManager. This happens mostly with devices where the 
interrupt port has a number > 0. I have yet to meet a GSM modem device 
where the "interrupt rule" does *not* apply.

I usually recommend using wvdial (autoprobing problems too) and edit 
the port directly in the config file. And just entering "gsmmodem" 
spares users the testing of all ports, some of which may seem to work 
at first but then build up a very unreliable connection.

> And what happens with your tool when in the near future, we want to talk
> to those other device nodes because modem-manager knows what thoes ports
> do and how to get the data out of them?


The usb_modeswitch helper in the post-switch rule only picks ttyUSB 
ports and looks only for their transfer type. It doesn't do anything 
to the ports if they are bulk.
Note that this is unrelated to the preceding switching process and 
doesn't change anything at all except that one symlink.

And yes, it can be scrapped anytime without further consequences when 
there are other solutions. It is a temporary workaround to make user's 
life a little easier.

> In short, you shouldn't have to do any of this.


I couldn't agree more! :-)


Regards,

Josua Dietze