Bug#982742: cups: config of usb printer now impossible due to usblp and libusb conficting (used to work!)

[mh <m.hatzold@web.de>]

Am Mon, 15 Feb 2021 10:26:52 +0000
schrieb Brian Potkin <claremont102@gmail.com>:

> On Sun 14 Feb 2021 at 20:31:28 +0100, mh wrote:
> 
> [...]
> 
> > # ippfind -T 5
> > ~#   
> 
> An IPP printer is not found. This would fit the observation that
> cups-browsed has not set up a print queue. I have come to the
> conclusion that the B432 does not implement IPP-over-USB correctly.

First: Thanks for your help and for all your efforts. But further
investigation and tests based on the new knowledge provided by you lets
me come to a different conclusion (see below). I didn't know about
ipp-usb, how it works and what it does and it automagically being
configured. 

> 
> A queue set up with a vendor PPD will not function while ipp-usb is
> active, so purge it and proceed as you did with the Live ISO. Also
> see #982190:
> 
>   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982190
> 
> Cheers,
> 
> Brian.

Purging ipp-usb instantly made the cups webinterface showing my
printer. So I could configure it using the vendor PPD file. Printing
menue (Libreoffice) shows one OKI printer. Print succeeded.
Thanks. 
So the main issue is solved as I can print from within my
default system. From what I've seen during configuration and printing,
the printer setup seems stabel, the printer showed up immediately, the
print job is carried out without much delay.

I then reinstalled ipp-usb which again prevented the cups webinterface
from seeing the printer. So clearly something around ipp-usb is broken.
I purged ipp-usb again and all is well.

I then investigated the LIVE-ISO. To my surprise ipp-usb is installed
within the LIVE-ISO. All the commands which failed/did have an empty
output on my default system work here with the expected output (I
guess), except for # avahi-browse -rt _ipp._tcp due to avahi-browse not
being installed:

# /usr/lib/cups/backend/usb
DEBUG: Loading USB quirks from "/usr/share/cups/usb".
DEBUG: Loaded 98 quirks.
DEBUG: list_devices
DEBUG: libusb_get_device_list=9
DEBUG: Failed to detach "usblp" module from 06bc:0357

# systemctl list-units "ipp-usb*" | grep service
  ipp-usb.service loaded active running Daemon for IPP over USB printer
support

# lpstat -t
Zeitplandienst läuft
Keine systemvoreingestellten Ziele
Gerät für OKI_DATA_CORP_B432:
ipp://OKI-B432-010E46%20(USB)._ipp._tcp.local/
OKI_DATA_CORP_B432 akzeptiert Anfragen seit Mo 15 Feb 2021 12:45:49 CET
Drucker OKI_DATA_CORP_B432 ist im Leerlauf.  Aktiviert seit Mo 15 Feb
2021 12:45:49 CET

# lpstat -l -e
OKI_B432_010E46_USB_ network none
ipp://OKI-B432-010E46%20(USB)._ipp._tcp.local/
OKI_DATA_CORP_B432 permanent
ipp://localhost/printers/OKI_DATA_CORP_B432
ipp://OKI-B432-010E46%20(USB)._ipp._tcp.local/

# avahi-browse -rt _ipp._tcp
Command 'avahi-browse' not found, but can be installed with:
apt install avahi-utils

I then tested my secound installation (the one based on the Live-ISO)
where I yesterday couldn't configure reliably my printer. I now realized
the printer can be configured here, too. I *suspect* this may have
happend because the printer wasn't switched off long enough or not at
all between unsuccessfull attempts and thus remaind in an undefined
state which then prevented a successfull configuration? Whether or not
the browser cache (which I emptied before every new attempt) played a
role, too ... I dont't know. Anyway, It now works here, too.


So it's my default system where the ipp-usb <-> printer communication
remains broken for whatever reason. This is a some years old and
comprehensive installation where this printer used to work until about a
year ago. Something subtle must have gone broken over time ... but I
can live with the printer not using ipp-usb as PPD is what I've allways
used.


@ till.kamppeter
As much as I'm willing to help, from what I can tell now I assume there
is not much to debug *direktly* related to the printer. Tell me if you
think otherwise.


BTW (not related the this malfunction):
There are already some OKI PPD files available in the cups config,
including the PPD file for the preceding model. Could I do anything to
help to include the appropriate vendor PPD file
for my printer (freely availabe on their webite) in the
printer-driver-oki package (or whichever package is the rightone)? 


Thanks

Michael