Comment 2 for bug 1512012

Hm. Some more testing revealed an odd difference between the USB ports on the left and on the back side of my docking station.

The back ports work as one would expect: printer is recognized and gets registered when plugged in, and gets unregistered when unplugged; USB drive when plugged in gets recognized and has its directory shown in Thunar (XFCE here).
The left-side ports show inconsistent behaviour: The USB drive gets recognized and has its directory shown, but plugging in the printer does not provoke even a single new line in /var/log/syslog.

I'm wondering how such a difference is even possible.

For reference, here's the syslog from plugging the Kyocera to a back-side port:

Oct 31 22:19:17 jodel kernel: [12061.944337] usb 3-1.2.1: new full-speed USB device number 16 using ehci-pci
Oct 31 22:19:17 jodel kernel: [12062.038199] usb 3-1.2.1: New USB device found, idVendor=0482, idProduct=0004
Oct 31 22:19:17 jodel kernel: [12062.038202] usb 3-1.2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Oct 31 22:19:17 jodel kernel: [12062.038204] usb 3-1.2.1: Product: Kyocera Mita FS-1900
Oct 31 22:19:17 jodel kernel: [12062.038205] usb 3-1.2.1: Manufacturer: Kyocera Mita
Oct 31 22:19:17 jodel kernel: [12062.038214] usb 3-1.2.1: SerialNumber: AAP2925070
Oct 31 22:19:17 jodel kernel: [12062.039274] usblp 3-1.2.1:1.0: usblp0: USB Bidirectional printer dev 16 if 0 alt 0 proto 2 vid 0x0482 pid 0x0004
Oct 31 22:19:17 jodel mtp-probe: checking bus 3, device 16: "/sys/devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.2/3-1.2.1"
Oct 31 22:19:17 jodel mtp-probe: bus: 3, device: 16 was not an MTP device
Oct 31 22:19:17 jodel systemd[1]: Starting Automatic USB/Bluetooth printer setup (-devices-pci0000:00-0000:00:1a.0-usb3-3\x2d1-3\x2d1.2-3\x2d1.2.1)...
Oct 31 22:19:17 jodel systemd[1]: Reached target Printer.
Oct 31 22:19:17 jodel udev-configure-printer[22613]: add /devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.2/3-1.2.1
Oct 31 22:19:17 jodel udev-configure-printer[22613]: device devpath is /devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.2/3-1.2.1
Oct 31 22:19:17 jodel udev-configure-printer[22613]: MFG:Kyocera MDL:FS-1900 SERN:- serial:AAP2925070
Oct 31 22:19:22 jodel kernel: [12067.091976] usblp0: removed
Oct 31 22:19:22 jodel kernel: [12067.094045] usblp 3-1.2.1:1.0: usblp0: USB Bidirectional printer dev 16 if 0 alt 0 proto 2 vid 0x0482 pid 0x0004
Oct 31 22:19:22 jodel udev-configure-printer[22613]: URI contains USB serial number
Oct 31 22:19:22 jodel udev-configure-printer[22613]: URI match: usb://Kyocera/FS-1900?serial=AAP2925070
Oct 31 22:19:22 jodel udev-configure-printer[22613]: URI of detected printer: usb://Kyocera/FS-1900?serial=AAP2925070, normalized: kyocera fs 1900 serial aap2925070
Oct 31 22:19:22 jodel udev-configure-printer[22613]: URI of print queue: dnssd://Xerox%20Phaser%206500DN%20(D6%3AA3%3AE5)._pdl-datastream._tcp.local/, normalized: dnssd xerox phaser 6500dn d6 a3 e5 pdl datastream tcp local
Oct 31 22:19:22 jodel udev-configure-printer[22613]: URI of print queue: usb://Kyocera/FS-1900?serial=AAP2925070, normalized: kyocera fs 1900 serial aap2925070
Oct 31 22:19:22 jodel udev-configure-printer[22613]: Queue ipp://localhost/printers/FS-1900 has matching device URI
Oct 31 22:19:22 jodel udev-configure-printer[22613]: Re-enabled printer ipp://localhost/printers/FS-1900
Oct 31 22:19:22 jodel systemd[1]: Started Automatic USB/Bluetooth printer setup (-devices-pci0000:00-0000:00:1a.0-usb3-3\x2d1-3\x2d1.2-3\x2d1.2.1).

(The Xerox is a network printer, reachable only through LAN.)

Unplugging syslog:

Oct 31 22:20:52 jodel kernel: [12157.332544] usb 3-1.2.1: USB disconnect, device number 16
Oct 31 22:20:52 jodel kernel: [12157.332719] usblp0: removed
Oct 31 22:20:52 jodel udev-configure-printer[22655]: remove /devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.2/3-1.2.1
Oct 31 22:20:52 jodel udev-configure-printer[22655]: URI of detected printer: usb://Kyocera/FS-1900?serial=AAP2925070, normalized: kyocera fs 1900 serial aap2925070
Oct 31 22:20:52 jodel udev-configure-printer[22655]: URI of print queue: dnssd://Xerox%20Phaser%206500DN%20(D6%3AA3%3AE5)._pdl-datastream._tcp.local/, normalized: dnssd xerox phaser 6500dn d6 a3 e5 pdl datastream tcp local
Oct 31 22:20:52 jodel udev-configure-printer[22655]: URI of print queue: usb://Kyocera/FS-1900?serial=AAP2925070, normalized: kyocera fs 1900 serial aap2925070
Oct 31 22:20:52 jodel udev-configure-printer[22655]: Queue ipp://localhost/printers/FS-1900 has matching device URI
Oct 31 22:20:52 jodel udev-configure-printer[22655]: Disabled printer ipp://localhost/printers/FS-1900 as the corresponding device was unplugged or turned off
Oct 31 22:20:52 jodel systemd[1]: printer.target: Unit not needed anymore. Stopping.
Oct 31 22:20:52 jodel systemd[1]: Stopped target Printer.

... this is getting weirder by the minute. Now the left-side USB ports show syslog messages, too.

Well, the test page is *still* wonky. That's not nice, but at least it's consistent...