[sane-devel] CanoScan LiDE30 problem

[Johannes Ranke]

* Gerhard Jaeger <gerhard at gjaeger.de> [071206 15:50]:
> On Thursday 06 December 2007 09:18:36 Johannes Ranke wrote:
> > Hi Gerhard and Gerard,
> > (replying to Gerard because I didn't receive Gerhards mail since I am
> > not on the list)
> > 
> > Thanks for the suggestion with CONFIG_USB_SUSPEND! I just booted a
> > self-compiled kernel without this option, and scanning works again from
> > the graphical frontends. What I don't understand is why it works from
> > the command line with scanimage, but not with the graphical frontends.
> > 
> 
> The GUI frontends are checking for the device and the release it.
> This is the point, where the USB subsystem waits some time and decides
> to go to the suspend mode - which the scanners don't like.

OK.
 
> scanimage itself, opens the device and scans without giving the USB
> subsystem the chance to go to sleep...
> 
> AFAIK, there's a workaround in more recent kernels, but I don't
> recall - maybe Julien?

Yes, I just read in a long Ubuntu forum thread, that in more recent
kernels, the possibility exists to exclude usb suspend to be active on
certain devices via udev rules. Together with a new sane version this
is supposed to fix the issue.
 
> Another workaround came to my mind: use the scanbutton daemon,
> which checks each 200ms for a pressed scanner button. That way,
> the USB won't also fell asleep...

Yes, I just saw that this workaround was mentioned in the forum thread
to be working, too. I guess this is THE workaround if you have a working
older kernel with CONFIG_USB_SUSPEND=y and don't want to upgrade.

Thanks a lot for your explanations!

Johannes

> 
> Ciao,
> Gerhard

-- 
Dr. Johannes Ranke                 jranke at uni-bremen.de     Key ID: F649AF90
UFT Bremen, Leobenerstr. 1         +49 421 218 63373
D-28359 Bremen                     http://www.uft.uni-bremen.de/chemie/ranke