Вернулся к попыткам подключить сканер, но так ничего и не получается. Интересно что sane-find-scanner его видит:

t1:~# sane-find-scanner
# sane-find-scanner will now attempt to detect your scanner. If the
# result is different from what you expected, first make sure your
# scanner is powered up and properly connected to your computer.

found USB scanner (vendor=0x03f0 [hewlett packard], product=0x2805 [hp scanjet],
chip=RTS8822) at libusb:001:002
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.

  А вот scanimage нет, хотя драйвер находится и подключается:

t1:~# SANE_DEBUG_DLL=255 scanimage -L
[sanei_debug] Setting debug level of dll to 255.
[dll] sane_init: SANE dll backend version 1.0.12 from sane-backends 1.0.19
[dll] sane_init: reading dll.conf
[dll] add_backend: adding backend `hp3900'
[dll] sane_get_devices
[dll] load: searching backend `hp3900' in `/usr/lib:/lib:/lib/sane'
[dll] load: trying to load `/usr/lib/libsane-hp3900.so.1'
[dll] load: couldn't open `/usr/lib/libsane-hp3900.so.1' (No such file or direct
ory)
[dll] load: trying to load `/lib/libsane-hp3900.so.1'
[dll] load: couldn't open `/lib/libsane-hp3900.so.1' (No such file or directory)
[dll] load: trying to load `/lib/sane/libsane-hp3900.so.1'
[dll] load: dlopen()ing `/lib/sane/libsane-hp3900.so.1'
[dll] init: initializing backend `hp3900'
[dll] init: backend `hp3900' is version 1.0.0
[dll] sane_get_devices: found 0 devices

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
[dll] sane_exit: exiting
[dll] sane_exit: calling backend `hp3900's exit function
[dll] sane_exit: finished

Что в таком случае можно попробовать? Почему sane_get_devices: found 0 devices ??