Re: USB gadget with drivers "on board"

[Josua Dietze]

MichaÅ Nazarewicz schrieb:

> On Mon, 26 Apr 2010 16:16:05 +0200, Daniel Mack <daniel@xxxxxxxx> wrote:
> > Are you sure they don't do exactly that by running two interfaces in
> > the same configuration?
>
> Yes, I'm sure.  I've investigated an USB GSM modem which, when plugged
> for the first time reports as mass storage (single configuration, single
> interface) and when drivers are installed as a full blown composite
> gadget.  I still haven't figured out how it does that.


These are the notorious mode switching devices. In Windows, they 
obviously install a special storage driver doing one specific action 
on each following plugging.
This action - some storage or control command - will "flip" the 
device, making it "disconnect" and returning as a completely different 
composite device.

Storage commands used for this procedure range from "SCSI rezero" over 
"passthrough" to "SCSI eject", or involve vendor specific stuff.


Josua Dietze

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