Praveen G K wrote:
Hello Mr. Viral Mehta,
I have posted this message on the linux-usb list. But, I have had no
response. Do you have any idea on this?
Thanks,
Praveen
---------- Forwarded message ----------
From: Praveen G K <praveen.gk@xxxxxxxxx>
Date: Mon, Aug 3, 2009 at 10:10 AM
Subject: Re: Bad USB Cable: Device Lockup in mass storage
To: linux-usb@xxxxxxxxxxxxxxx
On Fri, Jul 31, 2009 at 1:37 PM, Praveen G K<praveen.gk@xxxxxxxxx> wrote:
Hello all,
When I connect the device in mass storage mode using a bad USB cable,
my device locks up completely. Only a hard reset will help me get the
device back to normal functioning. This happens when the device is
connected to a windows box, but on a linux box, the device exits
gracefully, when it realizes it is not able to enumerate properly.
The linux host keeps sending the SET_ADDRESS command to the driver,
while the windows box sends a series of Get_Descriptor requests and
then enters the suspend state, and finally calls the unregister_driver
function.
All I can say is bus enumeration process in Windows and in Linux is
slightly different.
AFAIK, Linux assigns device address first and then asks for DD whereas
Windows asks for DD on default zero address.
There looks some relevance here. Btw, What do you want to solve
actually, 1. lock up in windows ? or 2. why it is not able to enumerate
on Linux ?
I dont even understand why do you want to debug a usecase of bad cable.
I don't understand why it is locking up, because I collected the debug
output from the fsg_unbind function in the file storage gadget file,
and I see all the debug output in the function call. I connected a
real view ICE debugger to see where it is locking up, and I notice
that the code is executing in the default_idle function in
arch/arm/kernel/process.c file.
Can show you many ways to debug on Linux but dont have much idea on how
to debug on Windows and ICE and etc. Never worked on this.
CCed to linux-usb as well, someone else will help you for sure.
Please let me know if you have any suggestions.
I am also attaching the debug log.
Thanks,
Praveen Krishnan
Thanks,
Viral Mehta,
Embedded Software Engineer,
Tel. No. 91 79 26563705, Ext. 423
www.einfochips.com <http://www.einfochips.com>
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