[sane-devel] Horizontal noise with Mustek ScanExpress 12000 SP Plus

[Henning Meier-Geinitz]

Hi,

On Sun, Nov 28, 2004 at 03:33:49PM +0100, spam@lsweb.de wrote:
> When hooking up my ScanExpress 12000 SP Plus to an Adaptec APA-1480
> Cardbus U-SCSI controller I get ugly horizontal lines in my color scans
> for resolutions exceeding 300 dpi.

I don't have such a scanner anymore but in comparison to the other
Mustek SCSI scanners it was of "very good nature". I.e. even if you
had tried to slow the computer down, it wouldn't have been confused by
backtracking the scan slider as other Mustek SCSI scanners.

> On my webserver you may find some example scans with accompanying debug
> logs for your analysis:
> * scanimage --mode Color --resolution 288 -t 150 -y 25 -v
> http://www.lsweb.de/images/sane/scan288dpi.log
> http://www.lsweb.de/images/sane/scan288dpi.jpg (works)
> * scanimage --mode Color --resolution 360 -t 150 -y 25 -v
> http://www.lsweb.de/images/sane/scan360dpi.log
> http://www.lsweb.de/images/sane/scan360dpi.jpg (screwed)
> * scanimage --mode Color --resolution 360 -t 150 -y 25 -v 
> http://www.lsweb.de/images/sane/scan360dpi_8MB.log
> http://www.lsweb.de/images/sane/scan360dpi_8MB.jpg (bigger buffer, but 
>                                                     still screwed)

As the backtracking (moving back and forth) of the scanhead is done by
the scanner itsself, there is nothing the backend can do. The stripes
really look like random data losses. Iit's not like the data is just
moved by some pixels.

> By the way, when hooked up to a Symbios Logic 53c875J controller there
> is no striping to be seen, so there seems to be some problem in
> conjunction with the APA-1480 (rev 03) hardware or the aic7xxx driver:

I'm pretty sure that this is a problem with either the SCSI controller
or the kernel SCSI driver. I've used various Adaptec SCSI host
adapters successfully but I don't know yours.

> Adaptec AIC7xxx driver version: 6.2.36
> Adaptec 1480A Ultra SCSI adapter
> aic7860: Ultra Single Channel A, SCSI Id=7, 3/253 SCBs
> Allocated SCBs: 5, SG List Length: 102
> <snip>
> Target 6 Negotiation Settings
>         User: 80.000MB/s transfers (80.000MHz, offset 127)
>         Goal: 3.300MB/s transfers
>         Curr: 3.300MB/s transfers

Maybe it's just too fast for that scanner? :-)

I guess you have checked that already but still: Termination and
cabling problems could cause such effects. I'd expect SCSI errors in
addition to that, however.

Bye,
  Henning