Oliver Neukum <[EMAIL PROTECTED]> said:
[ ... ]
>
> Firewire is a better design. There is no question about that.
> USB has no common protocol for transfering SCSI commands.
FireWire actually already does the SCSI encapsulation. The protocol
is called SBP2. Once you have a SBP2 device hooked up it will show
up as a SCSI device. This does work with scanners even under Linux
(I've an EPSON FireWire scanner running with Sane). There is nothing
to do on the Linux side to make this work, this is all done as part
of the protocol (and you need of course the SBP2 driver).
On the USB side it's not that easy - the USB scanners are all using
different protocols, so there is no common base that we can build
upon. But it's probably not that complicated either.
The question is if we really need this additional level of complexity.
All I would ask for is a function to query to vendor/prodoct ID of
a scanner. We know that all scanners will show up as /dev/usb/scannerX,
so when I'm looking for a scanner that is supported by my backend I
would only open all /dev/usb/scannerX devices and use the IOCTL to
get information about the device. If the backend can handle the
vendor/product ID it would use the device, otherwise it would go to
the next device.
I understand where Ed is comming from, his software supports all sorts
of scanners. In my case, I am only concerned about the EPSON scanners,
and it was trivial to implement the handling of SCSI and USB in the
backend. It's very likely not that trivial anymore if one has to do this
for multiple vendors.
Karl Heinz
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