Re: First version of modified Coolscan backend for the LS-30

Andreas Rick (rickand@gemse.fr)
Mon, 07 Jun 1999 16:07:24 +0200

Hi Nick

Thanks for your detailed problem description.
Unfortunately I don't have a quick answer for that
problem, as I face the same problem myself:

Nick Lamb wrote:
>
> 1. I downloaded an integrated the drivers with my SANE setup. I built
> the Coolscan stuff static and FTPed it to the scanner machine, which
> is a very minimal Linux install.
>
> 2. I checked find-scanner (looked good so far)
>
> 3. I ran scanimage -L and saw the Coolscan listed (yeah!)
>
> 4. I tried scanimage > example, but it locked up the SCSI on my test
> machine, and I had to switch off the Coolscan. The main drives on
> that machine are SCSI, so this was very scary. I shutdown & restarted

If I use the AM53C974 driver I have to reboot cold - I mean it locks
up my system completely without any chance to recover.
I only have IDE drives so I am less afraid to lose data on the disk
but it is extremely anoying anyway.

>
> /* I have a DPT card, using Linux 2.2.6 EATA card drivers. It wouldn't
> let go until I physically switched off the Coolscan :( */
>
> 5. I commented the AutoFocus code out of your driver
>
> 6. I re-built, re-transferred and re-installed
>
> 7. I ran scanimage > example, and this time I got some data!
>
> I'll write a second mail when I've tinkered with some more values and
> taken a look at the code a second time. However, I'm already impressed
> that I actually got DATA out of this first alpha driver.

Similar to your experience:
if I comment out the Autofocus code and use the AM53C974 driver
everything works fine. (except that the images are completly unsharp).
I have tried a little bit to figure out where the problem is,
but it seem to be inside the scsi-driver - not in SANE.
It is somewhat amazing, as the autofocus command doesn't distinguish
at all from all the other commands I send.

When using the tmscsi-driver everything works fine including autofocus
for the Coolscan-backend, but the UMAX backend doesn't finish its scanning
correctly (a problem already reported in the UMAX-FAQ).
Right now I have to switch SCSI-drivers if I want to switch from
my UMAX-Flatbed to the Coolscan-Filmscanner.

I was about to say that the AM53C974-driver might have some bug,
but when I use WINE and the TWAIN interface I can do everything until
I try to do use the autofocus. (prescan is OK, preview (which includes autofocus)
will crash). This behaviour is the same for the AM53C974 driver
and the tmscsi-driver.
It may be that the scanners answer to the command is somewhat unusual.

There is nothing much I can do at the SANE level as I am pretty
sure about the command to send (the same that TWAIN sends, the same that
vuescan sends)- the choices are:
don't do the autofocus-> image unsharp
do the autofocus -> system hangs.
None of the options is acceptable.
I think I will have to do some differential debugging (between the
AM53C974 driver and the tmscsi-driver) and as I'm not too experienced
in kernel-driver debugging this might take a while.

Any suggestions by SCSI-experienced people are very welcome.

Andreas

-------------------------------------------------------------
Andreas RICK e-mail: rickand@gemse.fr
-------------------------------------------------------------

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