Configuration of scanners in PLD

Main packages:

poldek:/all-avail> install sane-backends xsane

Display devices currently on USB bus (use sudo or make sure user in is usb group):

 /usr/sbin/lsusb

Plug in scanner, check /var/log/kernel for sth similar to:

Apr 15 10:34:27 laptop-hp kernel: [ 8122.892835] usb 2-1: new full speed USB device using ohci_hcd and address 4
Apr 15 10:34:27 laptop-hp kernel: [ 8123.078105] usb 2-1: New USB device found, idVendor=055f, idProduct=021b
Apr 15 10:34:27 laptop-hp kernel: [ 8123.078115] usb 2-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
Apr 15 10:34:27 laptop-hp kernel: [ 8123.078122] usb 2-1: Product: USB Scanner
Apr 15 10:34:27 laptop-hp kernel: [ 8123.078422] usb 2-1: configuration #1 chosen from 1 choice

or run lsusb again and notice new device.

Run (first from user account and later via sudo)

sane-find-scanner

One should see:

found USB scanner (vendor=0x055f, product=0x021b, chip=GT-6816?) at libusb:002:004

If there is also information

libusb couldn't open USB device /dev/bus/usb/002/004: Permission denied.
libusb requires write access to USB device nodes.

meaning there is privilages problem

If device being scanner has root:root privilates:

crw-rw-r-- 1 root root 189, 131 Apr 15 10:43 /dev/bus/usb/002/004

regular users will not be able to use scanner device.

Option is adding new udev rule to file /etc/udev/rules.d/41-libsane-local.rules which will deal with adding scanner device.

Selection criteria can be found from issuing command (after using proper usb bus numbers 2.4 in example):

udevadm info -a --name /dev/usbdev2.4 

or monitoring udev events (with properties display) during device plugin

udevadm monitor --property

Most likely criteria would be SYSFS{idVendor}== and SYSFS{idProduct} so rule migh look like:

SYSFS{idVendor}=="055f", SYSFS{idProduct}=="021b", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

Reload udev rules:

udevadm control --reload-rules

and unplug, plug device or trigger all rules again:

udevadm trigger

and verify results.

Note that we here try to use non-existing in PLD group 'scanner' but somehow rule works for me (udev-151, kernel-2.6.32.8) and something (TODO: what? by what criteria ?) adding currenly logged in on Xconsole user ? to device acl, so 'getfacl /dev/bus/usb/003/009' returns:

# file: 003/009
# owner: root
# group: root
user::rw-
user:matkor:rw-
group::rw-
mask::rw-
other::r--

and device is accesible (rw) for user 'matkor'.

Of course if above does not work, one can select any group 'usb', 'users' etc to be added for device.

Sometimes firmware file must be loaded to scanner before using it but required file(s) are not included with sane and must be downloaded from drivers/webpages. Run xsane from console and observere which files seems be needed for given scanner device.