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I'm running 20.04.2 LTS on a Dell Inspiron. While investigating another problem, I noticed that my /var/log/syslog is continually getting the USB device messages shown below. They come in at a rate > 1/second. Is this normal? This seems to be from the touchscreen.

Jun 17 19:01:24 GREY kernel: [  924.090073] usb 1-7: USB disconnect, device number 76
Jun 17 19:01:24 GREY fido_id[7641]: usb1: Failed to open report descriptor at '/sys/devices/pci0000:00/0000:00:14.0/usb1/report_descriptor': No such file or directory
Jun 17 19:01:24 GREY fido_id[7640]: usb1: Failed to open report descriptor at '/sys/devices/pci0000:00/0000:00:14.0/usb1/report_descriptor': No such file or directory
Jun 17 19:01:24 GREY kernel: [  924.486011] usb 1-7: new full-speed USB device number 77 using xhci_hcd
Jun 17 19:01:24 GREY kernel: [  924.634271] usb 1-7: not running at top speed; connect to a high speed hub
Jun 17 19:01:24 GREY kernel: [  924.635068] usb 1-7: New USB device found, idVendor=1fd2, idProduct=5001, bcdDevice= 5.00
Jun 17 19:01:24 GREY kernel: [  924.635070] usb 1-7: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Jun 17 19:01:24 GREY kernel: [  924.635071] usb 1-7: Product: LGD AIT Touch Controller
Jun 17 19:01:24 GREY kernel: [  924.635072] usb 1-7: Manufacturer: Melfas
Jun 17 19:01:24 GREY kernel: [  924.639056] input: Melfas LGD AIT Touch Controller as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/0003:1FD2:5001.09F1/input/input1565
Jun 17 19:01:24 GREY kernel: [  924.639177] hid-multitouch 0003:1FD2:5001.09F1: input,hiddev1,hidraw3: USB HID v2.00 Device [Melfas LGD AIT Touch Controller] on usb-0000:00:14.0-7/input0
Jun 17 19:01:24 GREY kernel: [  924.639761] hid-generic 0003:1FD2:5001.09F2: hiddev2,hidraw4: USB HID v1.00 Device [Melfas LGD AIT Touch Controller] on usb-0000:00:14.0-7/input1
Jun 17 19:01:24 GREY mtp-probe: checking bus 1, device 77: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-7"
Jun 17 19:01:24 GREY mtp-probe: bus: 1, device: 77 was not an MTP device
Jun 17 19:01:24 GREY kernel: [  924.690120] usb 1-7: USB disconnect, device number 77
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  • Not normal. The USB should not be disconnecting that way so frequently, so you know your problem, USB getting disconnected repeatedly. You may want to look at askubuntu.com/questions/814569/… , unix.stackexchange.com/questions/435229/… , askubuntu.com/questions/1021426/… Jun 18, 2021 at 6:36
  • It turns out that it is the touchscreen that is causing the issue, not the touchpad. The following did NOT help: /lib/udev/rules.d/77-mm-usb-device-blacklist.rules Added: ATTRS{idVendor}=="1fd2", ATTRS{idProduct}=="5001", ENV{ID_MM_TTY_BLACKLIST}="1" /etc/modprobe.d/blacklist.conf Added: blacklist usbtouchscreen blacklist hid_multitouch
    – Struttmann
    Jun 19, 2021 at 15:08

1 Answer 1

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Turns out to be a hardware problem with the touchscreen itself. Confirmed by attempting to run the Dell firmware ePSA diagnostics. Could not run any since they were hung at the main menu because the touchscreen was continually connecting/disconnecting. I found the laptop schematics and tried to find the surface-mounted fuse to remove to disable the touchscreen but, apparently, the fuse is mounted on the keyboard side of the motherboard and it would entail disconnecting 10+ fiddly connectors and removing the heat sink and that was just more work than I want to put into this at this time. So, I'll live with bloated syslogs for now.

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