Re: Howto change port used for 3g modem?

[perazim portugalmail pt]

Dan,

Although the 2.6.37 kernel works as advertised, it doesnn't work on my
Fedora 14 systems. There are a number of side effects introduced having
nothing to do with mm.

I have tried without success to patch the 2.6.35 Fedora 14 kernel with the
patch you wrote for the time-out problem.

Can you add this patch to the 2.6.35 Fedora 14 kernel? As I remember
when we started this discussion months ago you indicated this was possible.

Thanks,

Perazim

On Thu, 2011-05-12 at 21:29 +0100, perazim portugalmail pt wrote:
> Dan,
>
> Attached are the messages log and the modem-manager log for the Alcatel X220.
>
> Let me know if you need any other info or to test anything.

These logs indicate a kernel bug, with a 30 second hang when closing a
serial port.  I submitted a patch to the kernel to fix this issue which
was accepted for the 2.6.37 kernel:

commit 02303f73373aa1da19dbec510ec5a4e2576f9610
Author: Dan Williams <dcbw redhat com>
Date:   Fri Nov 19 16:04:00 2010 -0600

    usb-wwan: implement TIOCGSERIAL and TIOCSSERIAL to avoid blocking close(2)

    Some devices (ex ZTE 2726) simply don't respond at all when data is sent
    to some of their USB interfaces.  The data gets stuck in the TTYs queue
    and sits there until close(2), which them blocks because closing_wait
    defaults to 30 seconds (even though the fd is O_NONBLOCK).  This is
    rarely desired.  Implement the standard mechanism to adjust closing_wait
    and let applications handle it how they want to.

    Signed-off-by: Dan Williams <dcbw redhat com>

and the ModemManager snapshot you have should have the support necessary
here.  What kernel version are you running?

Dan