>> Hmmh, I don't think I would want to _force_ this behavior, since
>> it would slow down scanning by quite a bit. However, maybe we
>> could put an option into mustek.conf that lets you limit the
>> maximum distance scanned in one chunk. Then we can distribute
>> SANE with a mustek.conf that is safe for owners of an unpatched
>> Linux ncr810 driver. This leaves the option of getting back the
>> old behavior when it's known to be safe.
Rogier> The Tamarack looses 2 seconds on each "read". At 32k/read
Rogier> and 25Mb per scan, that comes to 2000 seconds. In this case
Rogier> the buffer size is the limiting factor.
OK, I ended up adding an option to the mustek.conf that is called
`strip-height'. It lets us limit the maximum strip height scanned with
a single SCSI command. The syntax is:
option strip-height HEIGHT
where HEIGHT is a floating point number specifying the height in
inches.
My plan is for all future SANE distributions will ship with a default
strip-height of 1 inch. This should be safe even for the ncr810
driver.
Limiting the strip-height does not seem to affect scan performance in
lineart and grayscale mode on my scanner (Paragon 600 II SP). The
story is quite different for color mode though:
strip-height: scan time (@ 18 dpi):
------------- ---------------------
1" 78sec
2" 56sec
unlimited 40sec
A strip-height of 2" seems to take about 7 seconds to scan, which is
about as close as I would want to get to the 10sec timeout in the
ncr810 driver. As you can see, this limit causes a slow down by 16
seconds, which certainly exceeds my level of patience. Thus, I'd
still recommend to patch the ncr810 driver where applicable and remove
the `strip-height' option. That will give you the old level of
performance. Note that you don't have to do anything if you have SANE
already installed and working---the "make install" step does not
overwrite existing configuration files, hence you don't have to worry
about getting slow scans when upgrading in the future.
BTW: Did anyone try out the pre0.62 patch? I haven't gotten any
reports so far.
--david
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