[sane-devel] Timeouts: usb_reset seems necessary to avoid bulk timeouts.

Karl Heinz Kremer khk@khk.net
Thu, 10 Jun 2004 05:36:52 -0400

I'm also reading sane-devel, so no need to take a detour with
any Epson backend related information :-)

I've never experienced any of the problem you describe, and I've
been running a 2.6.x kernel for some time now (SuSE 9.1 beta versions
and the final SuSE 9.1).

I've tried this with two different USB controllers (USB-1.1 and high
speed USB-2) with a number of different Epson scanners.

Karl Heinz

On Jun 10, 2004, at 12:02 AM, Olaf Meeuwissen wrote:

> Hi Tom,
> I am the lead developer of iscan and the sane-epkowa backend that
> comes with it.  Farideh has also contacted me about your issue, but I
> think that my reply is better sent to sane-devel (at least it'll be
> archived :-).
> Tom Schutzer-Weissmann <misc@tomweissmann.org> writes:
>> I had problems using the Epkowa libraries (libsane-epkowa) and the
>> iscan frontend with my usb scanner in kernel 2.6.
>> The scanner was closed after each operation. Once closed, nothing
>> could be read from it, and I got lots of BULK TIMEOUTs, although there
>> were no errors when the device was reopened.
> Sorry to say, but I can't reproduce your problem.  I've tried with a
> GT-8200 (aka Perfection 1650) on SuSE 9.1 and Debian (testing).  FWIW,
> the version of relevant packages:
>                             SuSE                  Debian
>   iscan                     1.8.1-0.redhat.8.0    1.8.1-0.redhat.8.0
>   sane                      1.0.13-73             --
>   libsane                   --                    1.0.14-2
>   libusb                    0.1.8-31              --
>   libusb-0.1-4              --                    0.1.8-11
>   kernel-default            2.6.4-52              --
>   kernel-image-2.6.6-1-686  --                    2.6.6-1
> with the note that I compiled iscan from sources on Debian.
> Can you give more information about your setup?  Things like scanner
> and distribution used as well as version of relevant software might
> help me in reproducing your problem.
> When you say that "Once closed, nothing could be read ...", do you
> mean the calls to sanei_usb_close?  I've looked at the debugging USB
> output and don't see any bulk timeouts.  My system logs also show
> nothing.
>> By modifying the code so that usb_reset() was always called before
>> usb_release_interface() and usb_close(), I solved the problem.
> The epkowa backend does not call the usb_* functions directly, so I
> presume you have been mucking around in sanei_usb, right?  This would
> seem to indicate that you think the problem is not specific to the
> epkowa backend.  I see below that you also get BULK TIMEOUTs with the
> epson backend.  Both backends share a lot of code, so this is not an
> indication that your problem is not backend specific.
> Has anyone seen this with other backends?
>> For libusb developers, my question is, should this be the case? There
>> is nothing in the API docs to indicate that it's necessary - perhaps
>> it is self-evident?
>> Farideh - in the belief that you are a point of contact for Epson
>> developers - could you make them aware of this issue, if they aren't
>> already.
> I read sane-devel ;-)
>> I think this is relevant to SANE because although I had some success
>> scanning with xsane and xscanimage, using the libsane-epson libraries,
>> I still got timeouts if I closed, say, xsane, and then restarted it -
>> for lack of a usb_reset() I believe.
> I have no problems closing iscan and restarting it (for the setups
> listed above).
>> Apologies if this is old news.  Tom SW
> Hope this helps,
> -- 
> Olaf Meeuwissen                            EPSON KOWA Corporation, PF1
> FSF Associate Member #1962           sign up at http://member.fsf.org/
> GnuPG key: 6BE37D90/AB6B 0D1F 99E7 1BF5 EB97  976A 16C7 F27D 6BE3 7D90
> Penguin's lib!       -- I hack, therefore I am --               LPIC-2
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