[sane-devel] canoscan 300 scsi scanner not detected

[Johannes Meixner]

Hello,

On Oct 28 09:52 m. allan noah wrote:
> I would need to check the code, but I think the canon backend mostly
> supports machines who's model name starts with 'IX' so the best
> solution might be:
>
> scsi CANON IX*
>
> or some such?

I do not have a scanner which is supported by the "canon" backend
so that all what I write here is only based upon what I read
somewhere.

According to what I read in "man sane-scsi"
---------------------------------------------------------------
     scsi VENDOR MODEL TYPE BUS CHANNEL ID LUN

... a field's value can be replaced with an asterisk
symbol (``*'').  An asterisk has the effect that any
value is allowed for that particular field.
---------------------------------------------------------------
so that it seems it is not possible to replace only a part
of a particular field with an asterisk.

According to
http://www.sane-project.org/sane-backends.html#S-CANON
the "canon" backend supports at least one non-CANON scanner,
the "Apple Color OneScanner 600/27".
I have no idea how this device shows up at the SCSI
but I assume Apple made sure that "their device" shows up
at the SCSI under a manufacturer name like "APPLE".

According to my tests in
http://lists.alioth.debian.org/pipermail/sane-devel/2006-May/016922.html
it seems it is not possible to have something like
-------------------------------------------------------------------
#canon.conf
scsi CANON
scsi APPLE
-------------------------------------------------------------------
because it seems only the last entry "scsi APPLE" is used then.

According to my tests in
http://lists.alioth.debian.org/pipermail/sane-devel/2006-May/016922.html
it seems not to cause problems if devices are probed
which are no scanners so that in the end our patch results
an unrestricted plain "scsi" by default in /etc/sane.d/canon.conf
-------------------------------------------------------------------
# canon.conf
#
# Activate exactly one of the following choices:
#
# Probe on all /dev/sg* devices:
scsi
#
# Probe for "CANON" on all /dev/sg* devices:
#scsi CANON
#
# Probe only on one fixed device:
#/dev/sg0
-------------------------------------------------------------------

We have this since July 2006 and at least I noticed no bug reports
or user complaints because of this - but I have no idea how many
users use scanners which are supported by the "canon" backend.

By default we have all backends in /etc/sane.d/dll.conf disabled
(to avoid that a SANE frontend lets various backends start up
and do needless probing for devices which do not exist)
so that the "canon" backend only runs for those users which
actually use a matching scanner.


Kind Regards
Johannes Meixner
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