Comment 55 for bug 85488

This from Sane-development-list:

Message: 3
Date: Mon, 16 Apr 2007 17:12:20 +0200
From: JKD <email address hidden>
Subject: Re: [sane-devel] Scanning produces black images
To: <email address hidden>
Message-ID: <email address hidden>
Content-Type: text/plain; charset=us-ascii

El Mon, 16 de Apr de 2007, a las 02:50:01PM +0200, Gerhard Jaeger dijo:
> > On Montag, 16. April 2007, JKD wrote:
> > [SNIPSNAP]
>>> > > > This is also an issue with the Plustek backend, reported by various
>>> > > > Ubuntu and Gentoo users. As already stated by PhobosK, the problem is
>>> > > > the kernel option CONFIG_USB_SUSPEND. This in deed is needed for laptop
>>> > > > users. It is currently marked as "experimental" but already used by various
>>> > > > distros.
>>> > > >
>> > >
>> > > That was my first thought. But if it's a kernel problem neither xsane
>> > > nor scanimage would scan successfully. And in two different compilations of
>> > > hp3900, ubuntu's one fails and my last compilation works.
>> > >
>>> > > > I think the problem really is, that libusb does not know anything about that
>>> > > > suspend stuff and therefore we have more or less no possibility to wakeup
>>> > > > the port, where the scanner is connected to.
>> > >
>> > > I think you're right. But may be libusb is already updated in debian
>> > > unstable. That would explain that my compilation works in ubuntu and
>> > > library provided by ubuntu in libsane-extras package doesn't. So my
>> > > conclusion would be the same. Backends need to be compiled against
>> > > current version of libusb.
> >
> > Could you please check which version of the libusb you/they use?

Debian:
 libusb-0.1-4 0.1.12-6
 libusb-dev 0.1.12-6

Ubuntu:
 libusb-0.1-4 0.1.12-2
 libusb-dev 0.1.12-2

>>> > > > One thing that could be observed: In all cases, scanimage works fine - guess
>>> > > > this is because it never closes the port until the scan process is done.
>> > >
>> > > I'm confused. Why should exist any difference between scanimage and xsane when
>> > > both frontends use the same SANE API to access usb scanners?
> >
> > Guess it's the workflow. When you call scanimage, then the scanner is openend,
> > detected, configured, scanning is done, closed.
> > XSane tries to open and detect, then closes a device. Then then scan is done
> > upon request. And I think after the first close, the device (or the port) will
> > be suspended.

I've compiled SANE backends in ubuntu. Instead of installing all project
I've just overwritten libsane-hp3900.la and libsane-hp3900.so.1.0.18 in
/usr/lib/sane with the ones generated in this compilation and xsane
works retrieving scanned image without problems.

Jonathan Bravo Lopez