On Sun, 11 Jan 2004, David Brownell wrote:

> Bill Unruh wrote:
> > If I plug in a Creative Soundblaster MP3 USB soundcard into the USB bus,   
> > the whole system halts (no reponse from anything-- only solution is a
> > hardware switchoff).
> > I narrowed it down to the ehci-hcd module by bringing up all modules
> > except it, and when it was brought up with the USB soundblaster plugged
> > in , the freeze happened again (note without the soundblaster plugged in
> > everything worked fine).
> 
> I'll be surprised if it's actually the "plugging in" rather than
> your usb audio driver binding to it.  You ought to be able to turn
> off hotplug temporarily (echo /bin/true > /proc/sys/kernel/hotplug),
> rmmod that audio driver, and then enumerate the device.
> 
> Is that a high speed device, or were you connecting a full speed
> device through a high speed hub?  The former should work with the
> latest EHCI patches (rewrite of highspeed iso support).  The latter
> won't work yet (someone would need to write it, using the highspeed
> support as a model), though it _should_ just fail gracefully.

I think it is a standard (1.1) USB device (Creative gives no technical
info on their products anywhere I could find-- not in the docs in the
box, or on their web page-- not even the bytes/sec the device supports.)
but I am not sure. 
I know that I turned off the echi_hcd modules, with the other modules
left running, (including the usb-audio module) and could see nothing on
any of the USB lines. If I started up the echi_hcd module, I got both
the light on the USB device turning on, and a freeze.

Unfotunately I have now returned the device to the store, so other
experiments will not work, at least not for a while.

By the latest ehci patches, you mean in which version of the kernel?
(2.4 series(?)).
Thanks for your attention.

Bill Unruh


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