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Frank Peters | 20 Aug 03:10
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2.6.26 Breaks USB Fax Modem

Hello,

After updating the kernel from 2.6.25 to 2.6.26, I now experience
severe problems when trying to send a fax using an external USB
modem.  Using either HylaFAX or efax facsimile software, the fax
transmission will just suddenly hang at some point before completion.
Neither the fax log or the kernel log will show any error or other
anomaly.  Rebooting the system with kernel 2.6.25 will allow me
to send faxes without problem.

Nothing on my machine has changed between 2.6.25 and 2.6.26 and
the same configuration was used to compile both versions. 

The cdc-acm module is responsible for communicating with the USB
modem and I suspect that it is at fault.

Has this problem been reported by anyone else?  How can I further
debug this problem?  As I mentioned, no log shows any error message
of any kind.  The logs from the fax software may indicate an
"unspecified error" but will usually just show that the data
stream has been abruptly halted.

Please cc to me directly since I am not subscribed to the list.

Frank Peters
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Oliver Neukum | 20 Aug 07:39

Re: 2.6.26 Breaks USB Fax Modem

Am Mittwoch 20 August 2008 03:10:39 schrieb Frank Peters:
> The cdc-acm module is responsible for communicating with the USB
> modem and I suspect that it is at fault.
> 
> Has this problem been reported by anyone else?  How can I further
> debug this problem?  As I mentioned, no log shows any error message
> of any kind.  The logs from the fax software may indicate an
> "unspecified error" but will usually just show that the data
> stream has been abruptly halted.

This is completely new. Please compile 2.6.26 with CONFIG_USB_DEBUG
and reexamine the log. It should be more verbose.

	Regards
		Oliver
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Frank Peters | 20 Aug 18:06
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Re: 2.6.26 Breaks USB Fax Modem

On Wed, 20 Aug 2008 07:39:51 +0200
Oliver Neukum <oliver@...> wrote:

> 
> This is completely new. Please compile 2.6.26 with CONFIG_USB_DEBUG
> and reexamine the log. It should be more verbose.
> 

In menuconfig, I enabled the USB_DEBUG option and then compiled
kernel 2.6.26.2.  The kernel log during a fax transmission is,
to my eyes, still not very revealing.

Before the fax is transmitted, the cdc-acm module is first loaded
with the commands:

modprobe cdc-acm
mount -t usbfs none /proc/bus/usb

Then the fax is sent with HylaFAX software.  (The problem is not
unique to  HylaFAX, however; it will occur with any fax software.)
HylaFAX will initialize the USB modem and then send the fax.  Here
is the kernel log:

Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: usb_probe_interface
Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: usb_probe_interface - got id
Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: ttyACM0: USB ACM device
Aug 20 10:53:22 (none) kernel: usbcore: registered new interface driver cdc_acm
Aug 20 10:53:22 (none) kernel: cdc_acm: v0.26:USB Abstract Control Model driver for USB modems and ISDN adapters
Aug 20 10:53:42 (none) kernel: uhci_hcd 0000:00:1a.1: reserve dev 2 ep84-INT, period 128, phase 0, 36 us
Aug 20 10:54:10 (none) kernel: uhci_hcd 0000:00:1a.1: release dev 2 ep84-INT, period 128, phase 0, 36 us
(Continue reading)

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Oliver Neukum | 20 Aug 18:12

Re: 2.6.26 Breaks USB Fax Modem

Am Mittwoch 20 August 2008 18:06:11 schrieb Frank Peters:
> On Wed, 20 Aug 2008 07:39:51 +0200
> Oliver Neukum <oliver@...> wrote:
> 
> > 
> > This is completely new. Please compile 2.6.26 with CONFIG_USB_DEBUG
> > and reexamine the log. It should be more verbose.
> > 
> 
> In menuconfig, I enabled the USB_DEBUG option and then compiled
> kernel 2.6.26.2.  The kernel log during a fax transmission is,
> to my eyes, still not very revealing.
> 
> Before the fax is transmitted, the cdc-acm module is first loaded
> with the commands:
> 
> modprobe cdc-acm
> mount -t usbfs none /proc/bus/usb
> 
> Then the fax is sent with HylaFAX software.  (The problem is not
> unique to  HylaFAX, however; it will occur with any fax software.)
> HylaFAX will initialize the USB modem and then send the fax.  Here
> is the kernel log:
> 
> Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: usb_probe_interface
> Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: usb_probe_interface - got id
> Aug 20 10:53:22 (none) kernel: cdc_acm 4-2:2.0: ttyACM0: USB ACM device
> Aug 20 10:53:22 (none) kernel: usbcore: registered new interface driver cdc_acm
> Aug 20 10:53:22 (none) kernel: cdc_acm: v0.26:USB Abstract Control Model driver for USB modems and ISDN adapters
> Aug 20 10:53:42 (none) kernel: uhci_hcd 0000:00:1a.1: reserve dev 2 ep84-INT, period 128, phase 0, 36 us
(Continue reading)

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Alan Stern | 20 Aug 20:53

Re: 2.6.26 Breaks USB Fax Modem

On Wed, 20 Aug 2008, Frank Peters wrote:

> > This is completely new. Please compile 2.6.26 with CONFIG_USB_DEBUG
> > and reexamine the log. It should be more verbose.

> If I immediately reboot the machine with kernel 2.6.25, the same fax
> can be sent to the same fax machine with no problem.

If all else fails, you could try bisecting the kernels between
2.6.25 and 2.6.26 to locate the problem.

Alan Stern

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Andrew Morton | 20 Aug 09:25

Re: 2.6.26 Breaks USB Fax Modem

On Tue, 19 Aug 2008 21:10:39 -0400 Frank Peters
<frank.peters@...> wrote:

> Hello,
> 
> After updating the kernel from 2.6.25 to 2.6.26, I now experience
> severe problems when trying to send a fax using an external USB
> modem.  Using either HylaFAX or efax facsimile software, the fax
> transmission will just suddenly hang at some point before completion.
> Neither the fax log or the kernel log will show any error or other
> anomaly.  Rebooting the system with kernel 2.6.25 will allow me
> to send faxes without problem.
> 
> Nothing on my machine has changed between 2.6.25 and 2.6.26 and
> the same configuration was used to compile both versions. 
> 
> The cdc-acm module is responsible for communicating with the USB
> modem and I suspect that it is at fault.
> 
> Has this problem been reported by anyone else?  How can I further
> debug this problem?  As I mentioned, no log shows any error message
> of any kind.  The logs from the fax software may indicate an
> "unspecified error" but will usually just show that the data
> stream has been abruptly halted.
> 
> Please cc to me directly since I am not subscribed to the list.
> 

(cc linux-usb)
(Continue reading)

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