Re: Snapscan USB hangs - compression?

From: Steve Underwood (
Date: Fri Jun 29 2001 - 06:29:09 PDT

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    John Coppens wrote:
    > Hello all.
    > No one bit the first time around. I still get hangs while transferring
    > images from the Snapscan scanner to the computer. A new hint: after
    > the hang, I try to rmmod the module 'uhci.o', which normally works,
    > then try to re-insmod it, which sometimes works, but at times segfaults
    > during initialization, and then cannot be removed.
    > I'd really appreciate a suggestion!
    > >
    > > I just recompiled sane/xsane for the 2.4.5 kernel I installed, hoping the
    > > problem would disappear, but no luck.
    > >
    > > When I scan (snapscan 1212U) an image with lots of white (probably
    > > saturated), the transmission to the PC hangs. Lowering contrast, or
    > > even turning the original 90 degrees, solves the problem. I suspect the
    > > image data is compressed when sending though USB. Could there be an
    > > bug in the protocol? Either in the Snapscan firmware, or at the receiving
    > > end?
    > >
    > > John

    A USB snapscan scanner uses exactly the same host communication protocol
    as a SCSI one, and no compression is used. Apart from that I can't help


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