[sane-devel] Scanner failure when connected via USB3

[Mike Cloaked]

On Tue, Oct 28, 2014 at 4:00 PM, Mike Cloaked <mike.cloaked at gmail.com>
wrote:

>
> OK - I have been working on this with a bit of free time today.   First to
> answer your question the vuescan scan of the sample document completed
> without error whereas the scan with xsane failed to complete and hung
> before it did very much which may explain the difference in the file sizes.
>
> Secondly i set up wireshark this afternoon, and got it all running to
> capture usb data on the bus that the scanner is connected to.  Having
> completed a capture for a vuescan run scanning the same docuument as
> previously. I then reset the scanner, and wireshark, and ran a scan in
> xsane - but instead of hanging it worked!  The only change since the
> previous time I booted the same laptop is that I ran a system update - but
> there was no obvious package that was updated that would have contributed
> to the changed behaviour!
>
> So I have the usb packet capture files for vuescan doing a single complete
> scan, a 2nd capture for xsane doing a pre-scan, and two runs where a full
> scan of the document at 300 dpi was made successfully with xsane with the
> scan window left untouched from the pre-scan, as well as one with the scan
> window set to the reduced image for the small document on the platten.
>
> However this is the first time that the scanner has ever worked to
> complete a scan with xsane.  I have looked through the package dependency
> tree to see which package may be a dependent one for xsane that was updated
> after booting the machine today. The only one was mesa and maybe mesa-dri
> but I would have been surprised if that update affected the scanner
> operation from within arch linux. I was also beginning to suspect the
> libusb package until today but that was not one of the packages that was
> updated.
>
> So right now I am perplexed, but I will boot the machine again in the next
> day or so, and run exactly the same test to see if it still works as it did
> today, and will report back on the outcome.  It would be nice to know if
> indeed one the the package updates did result in the change or if this it
> is that the scanner will most of the time still fail to work.
>
> I have the packet capture files as well as the packet-dissection text as a
> set of files, and after setting up the test again next time if the scan
> fails as usual I will capture the data for that as well.
>
>
I ran one final test before closing the machine down this evening.  The
scanner failed and hung when trying to trying to scan for devices.  At this
point I stopped wireshark and saved the files since the output was very
small.

The analysis showed malformed packets.  See attached files - which are
small enough to be accepted in this list as attachments.  The .pcapng file
can be replayed in wireshark.

I unplugged and re-plugged the scanner - and it was detected normally
showing normal systemd journal logging. Xsane connected to it and it
completed a full scan without error.  So it would seem that whether or not
the scanner works when connected to usb3 is intermittent. Sometimes it
initialises correctly and sometimes it does not.

I will run more tests and report when I can.

Mike

-- 
mike c
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