# Re: Problems with Acer ScanPrisa 640S

From: Sebastien Sable (sebastien.sable@gmx.net)
Date: Fri Oct 20 2000 - 17:53:57 PDT

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  Steve Underwood <steveu@coppice.org> writes:

  > I updated the backend to merge the colours properly in May. Since then I have had
  > little feedback. Lawrence is the first person to fully work through anything from
  > "I have a problem" to "I have a cure" since then. People need some serious coaxing

  This time I think "I have a cure" ;)

  I found that ps->pss->expected_read_bytes calculated in SCSISource_get
  was slowly decreasing down to 0. At this point
  (ps->pss->expected_read_bytes == 0) the scanner would block.

  To solve this, I can put it to an arbitrary high value.

  // ps->pss->expected_read_bytes =
  // ((int) (msecs/ps->pss->ms_per_line))*ps->pss->bytes_per_line;

  ps->pss->expected_read_bytes = 50000;

  then this line later
  ps->pss->expected_read_bytes = MIN(ps->pss->expected_read_bytes,
  (size_t) ps->absolute_max);
  put it to absolute_max.

  In this case, my scanner works fine and does not block anymore. Of
  course, it's a dirty trick.
  May be the ms_per_line reported by the scanner is not right or
  something?

      --
      Sébastien Sablé
      sebastien.sable@gmx.net
      --
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  - Next message: Chris Bagwell: "[snapscan] Small USB+misc patch for sane-1.0.3"
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