Arch Linux

MasterMax

Member

Registered: 2011-11-11

Posts: 21

brscan4 conflics with cups for Brother DCP 7055

Hi,

after installing brscan4 and running '/opt/brother/scanner/brscan4/setupSaneScan4 -i' the printer is no longer recognized by cups:

Installing the printer before installing brscan4 works great with the brother-dcp7055 package from AUR, but after installing brscan4 cups says 'Waiting for printer to become available'. When removing the printer, it is no longer found by cups, until uninstalling brscan4. Blacklisting usblp does not solve this problem. I reproduced this behavior on three arch machines, where a hp-printer/scanner combo works perfectly.

Any ideas?

jwm-art

Member

Registered: 2011-02-01

Posts: 87

Re: brscan4 conflics with cups for Brother DCP 7055

The device file is /dev/usb/lp0 with group ownership 'lp'. The brscan4 package changes this so that group ownership of /dev/usb/lp0 is 'scanner'. That's when the scanner starts working and printing stops working (ie waiting for printer...). This change is made by the udev rules created by the brscan4 package. If you edit the PKGBUILD then you can prevent the rules from being installed or you can simply rm /etc/udev/rules.d/brscan4.rules after the fact (and then retriggering udev).

There seems to be reports of both printer and scanner working without the rules by it didn't seem to work for me. The combination of 64bit system and DCP 7055 looked particularly problematic.

On my second evening of investigating this I looked into writing a rule to create an additional device node, but only symlinks can be created, and symlinks can't be used in such a way as to give access to the device via some other group.

I notice also that on the Arch Wiki user management page, the scanner and lp groups are listed as deprecated, so I decided to try this out by deleting those groups. The result being that neither the printer nor scanner could be used, soI re-created the scanner and lp groups, and added my user back into them.

Then I decided to try writing a udev rule that would call mknod to create a new device node which wasn't a symlink. First I needed to work out how to use mknod, and before long had a new character device /dev/usb/scanner alongside /dev/usb/lp0 both with a major number of 180 and minor number of 0.

I then discovered that this new character device wasn't removed when I unplugged the DCP 7055, and I'd still probably need some more udev magic to get this new device have group ownership by 'scanner' group.

I'm not exactly sure what happened next, but I tried printing and scanning and both worked. The udev rules are not in place, and I have rebooted and both printing and scanning still work. My suspicion is that the removal and re-creation of the lp and scanner groups did the trick, but I don't know how this could really be the case.

Last edited by jwm-art (2015-05-05 23:02:54)

Aximand

Member

From: Russia

Registered: 2009-11-15

Posts: 21

Re: brscan4 conflics with cups for Brother DCP 7055

The device file is /dev/usb/lp0 with group ownership 'lp'. The brscan4 package changes this so that group ownership of /dev/usb/lp0 is 'scanner'. That's when the scanner starts working and printing stops working (ie waiting for printer...). This change is made by the udev rules created by the brscan4 package. If you edit the PKGBUILD then you can prevent the rules from being installed or you can simply rm /etc/udev/rules.d/brscan4.rules after the fact (and then retriggering udev).

Thank you very much! Deleting the brscan4-rules worked like a charm for a Brother DCP-L2540DW

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pypi

Wiki Maintainer

Registered: 2014-04-22

Posts: 250

Re: brscan4 conflics with cups for Brother DCP 7055

Maybe a note on the wiki SANE page would be helpful for others?