Re: System hang (and other problems) with cdc_acm

[Oliver Neukum <oliver@neukum.org>]

Am Monday 26 January 2009 08:27:53 schrieb Andrew Morton:
> > I've got a Lenovo X200 with an Ericsson F3507g Mobile Broadband Module
> > (a 3G cellular data card with built-in GPS), which uses the cdc_acm
> > driver.  I've experienced a couple of problems with it.  First, it
> > tends to hang the system after I've been using it for a while.  This
> > occurs whenever it's sending a lot of data to/from the computer,
> > whether it's a PPP connection or a GPS data stream.  I'm not sure how
> > to debug this; the Caps Lock light isn't flashing, so I'm not sure if
> > it's a panic or just a hang.  Second, if I read one of the TTYs using
> > "cat", I get a ton of blank lines.  To make any sense of the data
> > stream, I have to do cat /dev/ttyACM0 | grep -v "^$".
> > 
> > If anyone could help me debug this, I'd be greatly appreciative.

It is probably necessary to setup a watchdog. Can you do that?
As for the blank lines, I am not sure this is a bug. Your device may
indeed send a lot of newlines.

	Regards
		Oliver