Public bug reported: Ubuntu 18.04.5 LTS Recently, after kernel update 4.15.0.144 (didn't know about the case yet), i can't open serial ports on USB CDC devices (STM32 Virtual COMs in my case).
using simple cat command (with or without sudo): $ sudo cat /dev/ttyACM1 cat: /dev/ttyACM1: Input/output error or some serial programs: Failed to connect to /dev/ttyACM1 : [Errno 5] could not open port /dev/ttyACM1: [Errno 5] Input/output error: '/dev/ttyACM1' dmesg: [ 3295.718270] cdc_acm 1-2:1.0: ttyACM1: USB ACM device [ 3302.508356] cdc_acm 1-2:1.0: acm_port_activate - usb_submit_urb(ctrl irq) failed [ 3302.508940] cdc_acm 1-2:1.0: acm_port_activate - usb_submit_urb(ctrl irq) failed When i try spamming commands while plugging the device in, i am sometimes able to open the port (might be the clue). When i booted in ubuntu advanced mode to 4.15.0.143 kernel, everything started to work normally. Also tried HWE stack with 5.4.0.74 kernel, but the bug was also present there. ** Affects: ubuntu Importance: Undecided Status: New ** Tags: acm cdc port serial usb -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1931684 Title: cdc_acm: acm_port_activate - usb_submit_urb(ctrl irq) failed To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1931684/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs