sane config files [was [sane-devel] Infrared channel]]

[Julien BLACHE]

"m. allan noah" <anoah@pfeiffer.edu> wrote:

>> In this case, the product ID will differ between the 2 hardwares (if
>> they're totally different, at least), or we can hope so. (talking of
>> USB here, as for everything else there's really no means to guess)
>
> no, you hope for too much. there are cases where manuf. makes changes

I hope that, in this case, the changes aren't too significant, that's
all. I learned the hard way that there's nothing you can hope from
hardware vendors (although some obviously behave better than others).

> to equipment capabilities (running changes) but does not update the

Hmm. There's a revision information along with the VID/PID which
basically covers this need. Is that usable in this situation ? (ie do
vendors care to update this one ?)

> PID. perhaps this case cannot be helped, and perhaps Oliver is right,
> that the backend will have to make options to disable these features.

Yep.

> then the serial number is useless to the discussion. the only reason
> to get it, is situations where there are multiple of the same scanner
> being used on a machine, and each needs a slightly different
> calibration. if per-scanner configs (gamma tables, etc) were stored by
> serial number this would work, even when the scanner switches ports or
> from scsi to usb.
>
> in order for this to work, the backend needs to be able to uniquely ID
> the unit.

This is needed too in cases where several identical scanners are
connected to the same host.

If only the USB spec made it mandatory to have a unique device
identifier :( [haven't read the spec for a long time now, but I don't
think something alike exists in the spec]

JB.

-- 
Julien BLACHE                                   <http://www.jblache.org> 
<jb@jblache.org>                                  GPG KeyID 0xF5D65169