Comment # 2 on bug 938659 from Johannes Meixner

Your initial description in comment#0 matches
https://bugzilla.suse.com/show_bug.cgi?id=920937#c23
and subsequent comments.

A bit later your call of /usr/lib/cups/backend/usb works
so that your symptoms also match the symptoms in
https://bugzilla.suse.com/show_bug.cgi?id=920937#c5
where for Sa��a Jani��ka /usr/lib/cups/backend/usb had worked
but he also got the "Failed to open device, code: -3".

In bug#920937 I wrote several times that I cannot help with
such issues, see
https://bugzilla.suse.com/show_bug.cgi?id=920937#c7
https://bugzilla.suse.com/show_bug.cgi?id=920937#c35
https://bugzilla.suse.com/show_bug.cgi?id=920937#c43
https://bugzilla.suse.com/show_bug.cgi?id=920937#c66


Regarding "YaST printer setup will keep or adjust the members
of the system group 'lp' appropriately":

The YaST printer setup does not and will not change system groups.

In general the YaST printer setup does not and will not change
basic system settings.

Accordingly the YaST printer setup also does not and will not change
device node permissions. That is done and has to be done by udev.

For example on my Tumbleweed system I get:
----------------------------------------------------------------------------
# lsusb
Bus 001 Device 002: ID 04f9:0022 Brother Industries, Ltd HL-5150D series
...

# ls -l /dev/bus/usb/001/002
crw-rw-r-- 1 root lp 189, 1 Jul 20 11:42 /dev/bus/usb/001/002

# lpinfo -v
...
direct usb://Brother/HL-5150D%20series?serial=F5J889574
...
----------------------------------------------------------------------------

Markus Elfring
what shows "ls -l /dev/bus/usb/<bus_number>/<device_number>"
for your USB printer device on your system?

The device node /dev/bus/usb/001/002 has "rw-rw-r-- 1 root lp"
because udev sets it for USB printer devices as far as I know via
/usr/lib/udev/rules.d/50-udev-default.rules
and
/usr/lib/udev/rules.d/99-systemd.rules

I think - but I am not at all a udev expert - that in
/usr/lib/udev/rules.d/50-udev-default.rules
the line (shown wrapped here - actually one line):
-----------------------------------------------------------------------------
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device",
 ENV{ID_USB_INTERFACES}=="*:0701??:*", GROUP="lp"
-----------------------------------------------------------------------------
sets group "lp" for USB printer devices.

Perhaps in special cases one may have to add MODE="0664"
to set device node access permissions explicitly to "rw-rw-r--"
as follows (all on one line shown wrapped only here):
-----------------------------------------------------------------------------
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device",
 ENV{ID_USB_INTERFACES}=="*:0701??:*", GROUP="lp", MODE="0664"
-----------------------------------------------------------------------------

Perhaps in special cases ENV{ID_USB_INTERFACES}=="*:0701??:*"
does not match for a particular USB printer device
so that one may have to use something else that matches?

In general when something with udev does not work as it should
I cannot help because I am not at all a sufficient udev expert.


As written in
https://bugzilla.suse.com/show_bug.cgi?id=920937#c43
https://bugzilla.suse.com/show_bug.cgi?id=920937#c66
https://bugzilla.suse.com/show_bug.cgi?id=920937#c113
https://bugzilla.suse.com/show_bug.cgi?id=920937#c130
I still think that the root cause of this issue
is very likely not in a "Printing" package but elsewhere
so that this issue does not belong to the Bugzilla
component "Printing".