Due to udev changes SANE stopped working - verified by downgrading to udev from stable branch

[Martin Pitt]

Hello Dirk,

Dirk Ritter [2015-07-07  3:11 +0200]:
> It drove me almost insane to try and debug SANE over
> the Weekend, but today I downgraded from udev / libudev1
> 221-1 to 215-17+deb8u1 and suddenly my flatbed scanner
> started to work again. No other changes whatsoever,
> using current SANE from testing, i.e. 1.0.24-13. The
> sole SANE backend used is "snapscan", driving the
> "EPSON Perfection 3490 Photo" which has (vendor=0x04b8
> [EPSON], product=0x0122 [EPSON Scanner]) at libusb:008:004
> according to sane-find-scanner. With current udev, this
> tool still finds the device (it merely scans the USB bus
> and reports everything advertising to be a scanner!),
> but SANE completely fails to recognize it, i.e.
> "scanimage -L" yields no results whatsoever for udev from
> testing, but works just fine with udev from stable.

Can you please compare permissions with the old and new udev? E. g.

  getfacl /dev/bus/usb/008/004

with the numbers that you got from above (bus and device number). Is
the new scanner somehow not accessible any more?

If it is, the next thing to try is to move away
/lib/udev/rules.d/42-usb-hid-pm.rules, and unplug/replug the scanner.
Does that change anything?

The next thing to try after that is if the breakage happens due to the
new /lib/systemd/systemd-udevd binary or the new /lib/udev/rules.d/
rules, i. e. could you test a mix of 221 binary and 215 rules and vice
versa?

Thanks,

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)