[Techtalk] USB problem

B Seeger seeger at prosensing.com
Fri Nov 30 14:29:46 UTC 2007


I work on an embedded device that has some USB issues.  First of all it
has a small computer with a compact flash card and no hard drive - so
linux runs in memory as a r/o operating system (ie changes you make to
it won't survive a reboot).  (not quite sure how to describe these
systems yet as it's the first one I've worked with) 

It's a linux 2.4.29 kernel with basic USB support.  The hardware we have
for the USB is a USB 1.1 port. 

Recently we've had issues getting USB sticks to work in this machine.
Supposedly USB 2.0 sticks should be backward compatible, but even if the
manufacturer says they are, I'm finding I'm having issues - some sticks
work, some don't. Even from the same manufacturer - supposedly the same
stick.  I'm using SanDisk Cruzers and if I open two new ones, one may
work, the other perhaps won't unless the sun is shining. 

We've been trying to trouble shoot this issue for a while -- questions
we've asked ourselves: is it the hardware?  Software?  Is the 2.0 stick
simply not getting enough power because it requires more then a 1.1
stick might?  

We mount the USB stick via a hotplug script and when I watch the log, I
see this message: 

hub.c: new USB device 00:0e.0-1, assigned address 2
scsi0 : SCSI emulation for USB Mass Storage devices
  Vendor: SanDisk   Model: U3 Cruzer Micro   Rev: 3.21
  Type:   Direct-Access                      ANSI SCSI revision: 02
usb_control/bulk_msg: timeout
host/usb-ohci.c: unlink URB timeout

The system should read a file off the stick and reboot, if necessary.
However, when this error message occurs, it doesn't read the stick and
just ignores it.

I haven't been able to uncover any solution to this problem and thought
you all might have some suggestions or advice... ??  Ultimately we think
we have to update the OS, but that's going to be alot of work for me,
and while I'm not against doing it, I'd like to make sure it's not
something else going on first.  


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