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

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

Am Sun, 14 Feb 2021 13:06:09 +0000
schrieb Brian Potkin <claremont102@gmail.com>:

> On Sun 14 Feb 2021 at 12:56:11 +0100, mh wrote:
> 
> > Am Sun, 14 Feb 2021 11:21:45 +0000
> > schrieb Brian Potkin <claremont102@gmail.com>:
> >   
> > > Michael, don't forget to mail the bug; I sent the last one there
> > > for you.  
> > 
> > Thanks. I wondered whether I should respond to your mail address.
> > Now I did CC 982742@bugs.debian.org if that's what you suggested.  
> 
> That's better. Thanks.
>  
> > > 
> > > "bInterfaceProtocol      4" indicates that the printer understands
> > > IPP=over-USB. Now give
> > > 
> > >   systemctl list-units "ipp-usb*" | grep service  
> > 
> > # systemctl list-units "ipp-usb*" | grep service
> > ~#  
> 
> An empty output is unexpected. What happens with
> 
>   systemctl start ipp-usb
> 
> and
> 
>   systemctl status ipp-usb
> 
> with the printer connected 

# systemctl start ipp-usb
~#

# systemctl status ipp-usb
● ipp-usb.service - Daemon for IPP over USB printer support
     Loaded: loaded (/lib/systemd/system/ipp-usb.service; static)
     Active: active (running) since Sun 2021-02-14 14:01:53 CET; 32min
ago Docs: man:ipp-usb(8)
   Main PID: 854 (ipp-usb)
      Tasks: 10 (limit: 4634)
     Memory: 7.9M
        CPU: 52ms
     CGroup: /system.slice/ipp-usb.service
             └─854 /sbin/ipp-usb udev

Feb 14 14:01:53 neutower systemd[1]: Started Daemon for IPP over USB
printer support.


> and disconnected?

(printer switched off)

~# systemctl status ipp-usb
● ipp-usb.service - Daemon for IPP over USB printer support
     Loaded: loaded (/lib/systemd/system/ipp-usb.service; static)
     Active: inactive (dead)
       Docs: man:ipp-usb(8)

Feb 14 14:01:53 neutower systemd[1]: Started Daemon for IPP over USB
printer support. Feb 14 14:37:24 neutower systemd[1]: ipp-usb.service:
Succeeded. Feb 14 14:38:18 neutower systemd[1]: Started Daemon for IPP
over USB printer support. Feb 14 14:38:18 neutower systemd[1]:
ipp-usb.service: Succeeded.


> 
> > > 
> > > and
> > > 
> > >   lpstat -t  
> > 
> > # lpstat -t
> > Zeitplandienst läuft
> > Keine systemvoreingestellten Ziele
> > lpstat: Keine Druckziele hinzugefügt.
> > lpstat: Keine Druckziele hinzugefügt.
> > lpstat: Keine Druckziele hinzugefügt.
> > lpstat: Keine Druckziele hinzugefügt.
> > 
> > Meaning:
> > time table service running
> > No preconfigured system targets
> > lpstat: No printing targets added.  
>  
> This is the expected output if ipp-usb is not active.
>  
> > BTW: I had IPP-USB configured once, but for that to happen I had to
> > connect the printer using a LAN cable. And I could not print either.
> > But there may have been other misconfigurations be involved, too,
> > as I didn't really understand how to configure a LAN connection for
> > the printer.   
> 
> IPP-over-USB is for a USB connection only. See sections 13, 14 and 15
> at
> 
>   https://wiki.debian.org/CUPSDriverlessPrinting

Thanks for the info.

> 
> 
> > *As a layman* I am guessing whether this USB mess happens due to
> > timing issues (live ISO is runing in RAM, so runs very responsive).
> > Shouldn't any solution involve solving the apparent conflict
> > between libusb and usblp?  
> 
> I am not skilled in USB matters and first wanted to discover whether
> the printing system is working as designed.

Ok, understood.

> 
> Regards,
> 
> Brian.

Greetings from Germany

Michael