[libvirt] Constantly changing USB product ID

[Philipp Hahn]

Hello Jaap,

On Thursday 29 March 2012 01:51:21 Jaap Winius wrote:
> Okay, thanks; so now I know that it's not just badly designed hardware
> that may do this. My device, however, is not a smart-phone or some
> other consumer device: it's a scanner with a rotating drum on which to
> mount flexible, reusable photographic plates from an X-ray machine.
> It's rather expensive too. Of course, it only works with a Windows
> application. Can you imagine a legitimate reason why a machine like
> this might keep flipping its product ID?

I know of some USB devices which use this trick to load there firmware: 
Initially the start without a firmware (so the manufacurer doesn't need to 
put a flash chip on the device) an USB-ID A. Windows detects the device using 
the ID and uploads the firmware to the device, which then soft-resets itself 
and re-appears with USB-ID B.

Sincerely
Philipp
-- 
Philipp Hahn           Open Source Software Engineer      hahn at univention.de
Univention GmbH        be open.                       fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/
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