usb scanner

[zontar]

I've got a Cannon LiDE 20 USB scanner that has been working perfectly with XSane for about a year, until today. Now I have permission problems. When I run XSane as a user, I get "no devices available". I can run it as root, everything works but I get scary messages about security. sane-find-scanner works for me as user, but scanimage -L says "no scanners identified". Both work as root. I ran through the steps in the wiki without any success. Maybe this is related to the new udev? I dont have a scanner rule in udev, I thought it was handled by libusb (but i'm out of my comfort zone). I could use some ideas on how to fix the permissions. Thanks.

[zontar]

Some additional information: I can make things work by adding devmode=0666 to the usbfs line in fstab. But this seem clumsy, and rather insecure (though it's only a home desktop machine). I do not have hotplug installed, just hotplug-base. But I've been scanning happily for months. I think I got hotplug-base when I installed udev. If memory serves, I got rid of hotplug because I got error messages about hotplug starting twice when I switched to udev.

[1U]

Is your user part of the usb group? I also use udev and i did not have to set any special permissions, being part of the usb group did it for me. Also I'd like to ask does your LiDe20 make any strange noises? I have the same exact scanner and it's twice as loud as it should be. I'm guessing the xsane drivers really tax the hardware compared to the ones from canon for windows, and I hope this does not shorten the life of the scanner.

[zontar]

Thanks for the idea, but no luck. I added myself to the usb group and got rid of the devmode in fstab and am back where I started. There's a script in /etc/hotplug/usb called libusbscanner that is supposed to set the permissions. It does not seem to be running, maybe because I am only using hotplug-base. As usual with this kind of thing, I wonder what update that I did in the last week changed things.

I actually fired up WinXP for the first time in months and tried out my scanner, after quickly doing a bunch of security updates. Indeed, it is a bit quieter. I noticed that it warmed up once when the computer booted up. Under Linux, it seems to warm up every time I use it causing some extra noise. And it does appear to run a bit noiser in general. Just my opinion, but I wouldn't worry too much about wear and tear. In my experience, scanners are pretty sturdy little guys.

[lbrtuk]

When something is accessed through libusb, a userspace app (via libusb) talks to a file in /proc/bus/usb/001/ (Might not be 001 for you. Not sure.)

Inside there, the devices themselves are filenames 001 002 006 etc.

So the trick is to see what the permissions of these files are by doing an ls -l on them. Then you can actually see what your problem is.

[zontar]

Thanks, lbrtuk, the file was /proc/bus/usb/002/002 and it had owner:group root:root and permissions 644. Somehow it's not getting changed by the /etc/hotplug/usb/libusbscanner script. I can change the permissions to 666 with a devmode=0666 in my fstab, but that makes everything usb world readable. (Probably OK on my machine, just sloppy.) I had no problem with this a couple of days before, and I wasn't even a member of the scanner group. Nice robot, by the way!

[1U]

Hehe it's the meetup of the robots!

Zontar,
Please let me know if you find a way to also make it a bit quieter and perform calibration/warmup a bit less. This thing is insanely loud.

[zontar]

Hey 1U,
You could open up /etc/sane.d/plustek.conf with your favorite editor and change "option warmup" to 0 and "option skipCalibration" to 1. I haven't tried this and wont guarantee that your scanner will like it. Worth a try, though. Mine really isn't that noisy. Noisier than under WinXP but not irksome.

[1U]

I did that but then it has streaking on the image. I wonder if there's a way to just do it once? Or which one would be responsible for streaks? Is it the warmup or the calibration?