Re: System hang (and other problems) with cdc_acm

[Andrew Morton <akpm@linux-foundation.org>]

(cc linux-usb)

On Mon, 19 Jan 2009 15:20:13 -0500 "Thomas Tuttle" <linux-kernel@ttuttle.net> wrote:

> Hi.
> 
> 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.
> 
> Thanks,
> 
> Thomas Tuttle