Problems with ttyUSB0, it doesnt stick around!

Background… I purchased the new Librem 14 to be my on prem workhorse and so far with some tweaks to PureOS I have been able to get everything I need to work, work, except for accessing USB based console cables. I have two USB-C and one USB-A based cable and none work with the new PureOS (10) that come by default on the new Librems.

These cables work on my MacBook, Lenovo P52s (Winders), and my System76 (PopOS), but not here.

Another strainge behaviour that I noticed is when you plugin the cable the OS does recognize it and lables it ttyUSB0 in /dev, however, it is only there for roughly 3 seconds before disappearing, never to be seen again. Unless unplugged and then plugged back in of course.

This brings me to my questions:

  1. Does anyone else experience this?
  2. How on earth do I troubleshoot this?
  3. Finally, how do I fix this (please let some genius see this and fix whatever driver has the bug and release it in the next batch of updates ;-)?

What does journalctl show when you connect the cables?

Nothing seems related in journalctl, tail of plugin cycle below:

Aug 12 14:01:43 JJsPure gnome-shell[1683]: libinput error: event0 - AT Translated Set 2 keyboard: client bug: event processing lagging behind by 34ms, your system is too slow
Aug 12 14:02:09 JJsPure gnome-shell[1683]: Window manager warning: last_user_time (78517681) is greater than comparison timestamp (78517643). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around…
Aug 12 14:02:09 JJsPure gnome-shell[1683]: Window manager warning: W0 appears to be one of the offending windows with a timestamp of 78517681. Working around…
Aug 12 14:02:09 JJsPure gnome-shell[1683]: libinput error: event0 - AT Translated Set 2 keyboard: client bug: event processing lagging behind by 20ms, your system is too slow
Aug 12 14:02:09 JJsPure gnome-shell[1683]: Window manager warning: last_user_time (78517992) is greater than comparison timestamp (78517959). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around…
Aug 12 14:02:09 JJsPure gnome-shell[1683]: Window manager warning: W0 appears to be one of the offending windows with a timestamp of 78517992. Working around…
Aug 12 14:02:58 JJsPure vivaldi-stable.desktop[13942]: [13977:13981:0812/140258.666922:ERROR:ssl_client_socket_impl.cc(981)] handshake failed; returned -1, SSL error code 1, net_error -202
Aug 12 14:02:59 JJsPure vivaldi-stable.desktop[13942]: [13977:13981:0812/140259.137656:ERROR:ssl_client_socket_impl.cc(981)] handshake failed; returned -1, SSL error code 1, net_error -202
Aug 12 14:02:59 JJsPure vivaldi-stable.desktop[13942]: [13977:13981:0812/140259.139548:ERROR:ssl_client_socket_impl.cc(981)] handshake failed; returned -1, SSL error code 1, net_error -202

/var/log/messages did have info:
ug 12 14:10:35 JJsPure kernel: [79023.537782] usb 1-7: SerialNumber: A9489PPU
Aug 12 14:10:35 JJsPure kernel: [79023.541546] ftdi_sio 1-7:1.0: FTDI USB Serial Device converter detected
Aug 12 14:10:35 JJsPure kernel: [79023.541638] usb 1-7: Detected FT232RL
Aug 12 14:10:35 JJsPure kernel: [79023.543192] usb 1-7: FTDI USB Serial Device converter now attached to ttyUSB0
Aug 12 14:10:35 JJsPure mtp-probe: checking bus 1, device 32: “/sys/devices/pci0000:00/0000:00:14.0/usb1/1-7”
Aug 12 14:10:35 JJsPure mtp-probe: bus: 1, device: 32 was not an MTP device
Aug 12 14:10:35 JJsPure upowerd[1084]: treating change event as add on /sys/devices/pci0000:00/0000:00:14.0/usb1/1-7
Aug 12 14:10:35 JJsPure mtp-probe: checking bus 1, device 32: “/sys/devices/pci0000:00/0000:00:14.0/usb1/1-7”
Aug 12 14:10:35 JJsPure mtp-probe: bus: 1, device: 32 was not an MTP device
Aug 12 14:10:35 JJsPure kernel: [79023.543192] usb 1-7: FTDI USB Serial Device converter now attached to ttyUSB0
Aug 12 14:10:35 JJsPure mtp-probe: checking bus 1, device 32: “/sys/devices/pci0000:00/0000:00:14.0/usb1/1-7”
Aug 12 14:10:35 JJsPure mtp-probe: bus: 1, device: 32 was not an MTP device
Aug 12 14:10:35 JJsPure upowerd[1084]: treating change event as add on /sys/devices/pci0000:00/0000:00:14.0/usb1/1-7
Aug 12 14:10:35 JJsPure mtp-probe: checking bus 1, device 32: “/sys/devices/pci0000:00/0000:00:14.0/usb1/1-7”
Aug 12 14:10:35 JJsPure mtp-probe: bus: 1, device: 32 was not an MTP device
Aug 12 14:10:40 JJsPure kernel: [79028.553642] usb 1-7: usbfs: interface 0 claimed by ftdi_sio while ‘brltty’ sets config #1
Aug 12 14:10:40 JJsPure kernel: [79028.554703] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
Aug 12 14:10:40 JJsPure kernel: [79028.554719] ftdi_sio 1-7:1.0: device disconnected

Not that it means much to me.

[21080.215371] cp210x 1-7:1.0: cp210x converter detected
[21080.217422] usb 1-7: cp210x converter now attached to ttyUSB0
[21083.393111] usb 1-7: usbfs: interface 0 claimed by cp210x while ‘brltty’ sets config #1

yes
issue is related to brltty picking up this device
fix would be:
$ sudo apt purge brltty

unless you need breil terminal :stuck_out_tongue_winking_eye:

1 Like

Thanks for bailing me out there. I don’t know what I was thinking when t-shooting it the first time… I must of had a senior moment. :frowning:

glad was able to help.
btw it’s known issue, and was fixed in ubuntu, so maybe fix will came to debian so to pureos too.
it’s a bug in brltty trying to pickup any usb serial device it finds.