In a message dated 5/3/2001 3:19:34 AM EST, moitinho@civil.ist.utl.pt writes:
> I have read the arguments in favour of different drivers, you don't need to
> try to explain, but I still don't understand why (for instance) the
> usb-storage driver doesn't work (at least id didn't). Just my problem of
> thinking that I understand what I don't.
There's no good reason why a single driver shouldn't serve
as a scsi->usb device driver for all devices that need to look
like a scsi device to higher level routines.
Oliver claims this would be too hard to write, but I've done it
on Windows and Mac OS and it isn't hard. The upper levels
of VueScan think they're working with SCSI scanners, and
at the lowest level I translate scsi commands to USB
commands. The trick is to design the driver to do this from
the start. This works today on Windows and Mac OS with
HP, Epson, Avision, Acer, and AGFA USB scanners. I did
the same thing with Firewire scanners on Windows, since
they also encapsulate scsi commands on Firewire (SBP2
protocol). Someone already did a generic scsi->firewire
driver on Linux, and a similar scsi-usb driver is all that's needed.
Note that the advantage of using generic scsi->usb and
scsi->firewire drivers is that there isn't any need to set
up configuration files specifying which scanners (and
what type of scanners) are on the system. The nice
part of scsi is that it's possible to poll each device to find
out what kind of device it is, instead of depending on the
user to set this up (this is a lot more user-friendly). This
is how VueScan works.
This driver the kind of thing I'd assign a college intern or
beginning programmer to do - it's not hard. If nobody on
this list has any kernel programming experience, I'll do it
myself in a month or two as soon as I finish some higher
priority tasks in VueScan. However, if I write it, I plan to
sell it (it won't be open source). If someone wants to
write it and make it open source, I'd be happy to provide
them the technical assistance they'd need to get it working
with a wide range of usb scanners.
Regards,
Ed Hamrick
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