Now I find that I gathered enough technical details for such a bug report which
is a successor for my clarification request "YaST connection assistant does not
show a working printer on USB port.".
https://forums.opensuse.org/showthread.php/508345-YaST-connection-assistant-does-not-show-a-working-printer-on-USB-port

I have installed the software "CUPS 2.0.3-180.1" a moment ago.
http://download.opensuse.org/repositories/Printing/openSUSE_Tumbleweed/

The command "/usr/sbin/cupsd -l" is running since this installation succeeded.

I would like to clarify the following display again while my idle USB printer
is connected and should be usable.

Sonne:~ # /usr/sbin/lpinfo -v
network lpd
network https
network socket
network ipps
network http
network smb
network ipp
direct hp
serial serial:/dev/ttyS0?baud=115200


Now I wonder that the file "/var/log/cups/error_log" was not written despite of
the setting "debug2" for the parameter "LogLevel" in the file
"/etc/cups/cupsd.conf".
So I stop this process and restart the print server.

Sonne:~ # kill 5144 && /usr/sbin/cupsd


Then another try for the desired device detection ���

Sonne:~ # /usr/sbin/lpinfo -v
network lpd
direct hp
network smb
serial serial:/dev/ttyS0?baud=115200
network https
network socket
network ipps
network http
network ipp


The file "/var/log/cups/error_log" was written this time. It contains the
message "[CGI] Failed to open device, code: -3".
I determined the function "open_device" from the source file "usb-libusb.c" of
the affected CUPS backend as the origin for this information. The shown return
value from a call of the function "libusb_open" corresponds to the preprocessor
symbol "LIBUSB_ERROR_ACCESS".
https://github.com/libusb/libusb/blob/c141457debff6156b83786eb69b46d873634e5bd/libusb/libusb.h#L1064

Would you like to help me further with the determination and setting of
appropriate permissions for a working print system configuration?


Sonne:~ # /usr/lib/cups/backend/usb
DEBUG: Loading USB quirks from "/usr/share/cups/usb".
DEBUG: Loaded 114 quirks.
DEBUG: list_devices
DEBUG: libusb_get_device_list=5
DEBUG2: Printer found with device ID: ID:ECOSYS
P6021cdn;MFG:Kyocera;CMD:PCLXL,PostScript Emulation,PCL5C,PJL;MDL:ECOSYS
P6021cdn;CLS:PRINTER;DES:Kyocera ECOSYS P6021cdn;CID:KY_XPS_ColorA4FID; Device
URI: usb://Kyocera/ECOSYS%20P6021cdn?serial=LW44818568
direct usb://Kyocera/ECOSYS%20P6021cdn?serial=LW44818568 "Kyocera ECOSYS
P6021cdn" "Kyocera ECOSYS P6021cdn" "ID:ECOSYS
P6021cdn;MFG:Kyocera;CMD:PCLXL,PostScript Emulation,PCL5C,PJL;MDL:ECOSYS
P6021cdn;CLS:PRINTER;DES:Kyocera ECOSYS P6021cdn;CID:KY_XPS_ColorA4FID;" ""