[sane-devel] R: Re: R: Re: R: Re: scanner Epson DX4250 not working in Ubuntu 11.10

[Giorgio F. Signorini]

Maybe I should point out here that the same scanner (with the same USB
cable!) works well on my laptop: Ubuntu 10.10, with
    xsane: 0.997-2ubuntu3
    libsane: 1.0.21-2ubuntu2

Problems arise only with my desktop: Ubuntu 11.10, with
    xsane: 0.998-3ubuntu1
    libsane: 1.0.22-2ubuntu2

The same happens to other users 
[see https://bugs.launchpad.net/simple-scan/+bug/888267]

>From what you say I suspect that the problem might be in the USB
management

** ubuntu 10.10 **
libusb-0.1-4 -> 2:0.1.12-15ubuntu2 
libusbmuxd1  -> 1.0.4-1
libusb-1.0-0 -> 2:1.0.8-2                             


** Ubuntu 11.10 **
libusb-0.1-4 -> 2:0.1.12-18
libusbmuxd1  -> 1.0.7-1ubuntu0.11.10.1
libusb-1.0-0 ->  2:1.0.8-4

Would it be useful/possible/advisable to downgrade these? 

Giorgio

 > From: Olaf Meeuwissen <olaf.meeuwissen at avasys.jp>
 > Date: Fri, 27 Apr 2012 08:01:24 +0900
 > 
 > Richard Ryniker <ryniker at alum.mit.edu> writes:
 > 
 > >>Now it is guess work why the device is temporarily unavailable when
 > >>trying to reset it, but replies just fine to the status query to comes
 > >>immediately after.
 > >
 > > Timing issue?  Perhaps the two bytes written to the device start some
 > > action that has not completed before the read request is tried,
 > > therefore the "Resource temporarily unavailable" status.
 > 
 > The two bytes written to the device cause a reset.  All that needs to be
 > done is initializing a limited number of values in the firmware, nothing
 > that takes a significant about of time.
 > 
 > > If the read operation is retried, it might succeed.
 > 
 > That's something the backend should be doing to begin with when this
 > particular condition happens during USB I/O but the sanei_usb wrapper
 > merely returns SANE_STATUS_IO_ERROR so there no way you can tell what
 > went wrong.  For all the backend knows the USB might have been pulled
 > or the device could have been turned off.
 > 
 > Hope this helps,
 > -- 
 > Olaf Meeuwissen, LPIC-2           FLOSS Engineer -- AVASYS CORPORATION
 > FSF Associate Member #1962               Help support software freedom
 >                  http://www.fsf.org/jf?referrer=1962