Merlin 378.56_2 - Asus RT-AC56U - missing support for MFP scanner (Samsung SCX-4100)

[Quadcore]

I've a problem with Merlin 378.56_2, my MFP printer Samsung SCX-4100 is recognized and can print but scanner doesn't work.
I've already read following thread (https://github.com/RMerl/asuswrt-merlin/wiki/Network-Scanning-With-Sane), I have also added SCX-4100 printer inside /opt/etc/sane.d/xerox_mpf.conf (usb 0x04e8 0x3413), but nothing to do, scanner doesn't work.
If I run “sane-find-scanner -v”, it searchs for usb scanners in /dev/usb/* and /dev/usbscanner, but it doens't find any device (the only device included in /dev/usb is lp0 for the printer).
I've even created node /dev/usb/usbscanner0 as described here (http://tldp.org/HOWTO/Scanner-HOWTO/dev-intro.html#DEVFSD), but scanner still doesn't work.
Any hints, tips or suggestions to let scanner work? Thanks.

uname -a
Linux RT-AC56U 2.6.36.4brcmarm #1 SMP PREEMPT Mon Nov 2 10:06:35 EST 2015 armv7l GNU/Linux

scanimage
scanimage: no SANE devices found

scanimage -L
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).

scanimage -t
scanimage: no SANE devices found

sane-find-scanner -v
This is sane-find-scanner from sane-backends 1.0.22

# 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.

searching for SCSI scanners:
checking /dev/scanner... failed to open (Invalid argument)
checking /dev/sg0... failed to open (Invalid argument)
checking /dev/sg1... failed to open (Invalid argument)
checking /dev/sg2... failed to open (Invalid argument)
checking /dev/sg3... failed to open (Invalid argument)
checking /dev/sg4... failed to open (Invalid argument)
checking /dev/sg5... failed to open (Invalid argument)
checking /dev/sg6... failed to open (Invalid argument)
checking /dev/sg7... failed to open (Invalid argument)
checking /dev/sg8... failed to open (Invalid argument)
checking /dev/sg9... failed to open (Invalid argument)
checking /dev/sga... failed to open (Invalid argument)
checking /dev/sgb... failed to open (Invalid argument)
checking /dev/sgc... failed to open (Invalid argument)
checking /dev/sgd... failed to open (Invalid argument)
checking /dev/sge... failed to open (Invalid argument)
checking /dev/sgf... failed to open (Invalid argument)
checking /dev/sgg... failed to open (Invalid argument)
checking /dev/sgh... failed to open (Invalid argument)
checking /dev/sgi... failed to open (Invalid argument)
checking /dev/sgj... failed to open (Invalid argument)
checking /dev/sgk... failed to open (Invalid argument)
checking /dev/sgl... failed to open (Invalid argument)
checking /dev/sgm... failed to open (Invalid argument)
checking /dev/sgn... failed to open (Invalid argument)
checking /dev/sgo... failed to open (Invalid argument)
checking /dev/sgp... failed to open (Invalid argument)
checking /dev/sgq... failed to open (Invalid argument)
checking /dev/sgr... failed to open (Invalid argument)
checking /dev/sgs... failed to open (Invalid argument)
checking /dev/sgt... failed to open (Invalid argument)
checking /dev/sgu... failed to open (Invalid argument)
checking /dev/sgv... failed to open (Invalid argument)
checking /dev/sgw... failed to open (Invalid argument)
checking /dev/sgx... failed to open (Invalid argument)
checking /dev/sgy... failed to open (Invalid argument)
checking /dev/sgz... failed to open (Invalid argument)
# No SCSI scanners found. If you expected something different, make sure that
# you have loaded a kernel SCSI driver for your SCSI adapter.

searching for USB scanners:
checking /dev/usb/scanner... failed to open (Invalid argument)
checking /dev/usb/scanner0... failed to open (Invalid argument)
checking /dev/usb/scanner1... failed to open (Invalid argument)
checking /dev/usb/scanner2... failed to open (Invalid argument)
checking /dev/usb/scanner3... failed to open (Invalid argument)
checking /dev/usb/scanner4... failed to open (Invalid argument)
checking /dev/usb/scanner5... failed to open (Invalid argument)
checking /dev/usb/scanner5... failed to open (Invalid argument)
checking /dev/usb/scanner7... failed to open (Invalid argument)
checking /dev/usb/scanner8... failed to open (Invalid argument)
checking /dev/usb/scanner9... failed to open (Invalid argument)
checking /dev/usb/scanner10... failed to open (Invalid argument)
checking /dev/usb/scanner11... failed to open (Invalid argument)
checking /dev/usb/scanner12... failed to open (Invalid argument)
checking /dev/usb/scanner13... failed to open (Invalid argument)
checking /dev/usb/scanner14... failed to open (Invalid argument)
checking /dev/usb/scanner15... failed to open (Invalid argument)
checking /dev/usbscanner... failed to open (Invalid argument)
checking /dev/usbscanner0... failed to open (Invalid argument)
checking /dev/usbscanner1... failed to open (Invalid argument)
checking /dev/usbscanner2... failed to open (Invalid argument)
checking /dev/usbscanner3... failed to open (Invalid argument)
checking /dev/usbscanner4... failed to open (Invalid argument)
checking /dev/usbscanner5... failed to open (Invalid argument)
checking /dev/usbscanner6... failed to open (Invalid argument)
checking /dev/usbscanner7... failed to open (Invalid argument)
checking /dev/usbscanner8... failed to open (Invalid argument)
checking /dev/usbscanner9... failed to open (Invalid argument)
checking /dev/usbscanner10... failed to open (Invalid argument)
checking /dev/usbscanner11... failed to open (Invalid argument)
checking /dev/usbscanner12... failed to open (Invalid argument)
checking /dev/usbscanner13... failed to open (Invalid argument)
checking /dev/usbscanner14... failed to open (Invalid argument)
checking /dev/usbscanner15... failed to open (Invalid argument)
# No USB scanners found. If you expected something different, make sure that
# you have loaded a kernel driver for your USB host controller and have setup
# the USB system correctly. See man sane-usb for details.

# Not checking for parallel port scanners.

# Most Scanners connected to the parallel port or other proprietary ports
# can't be detected by this program.
Done

 

[RMerlin]

I have no intention on supporting scanners.

 

[Eugene Paskevich]

I've made scx-4100 scanner work with original asuswrt (AC87U) and arm binaries from the UnifiedLinuxDriver-1.00.29.tar.gz package from suldr site.
Yes, quite a lot of stracing and plugging the holes, but it works in the end. It is required to reset USB channel after each scanning though. :-(
Alas, I have no idea how to automate that reset.