Bugzilla – Bug 1217291
Kernel 6.6 regression: Wacom tablet detected as USB hub
Last modified: 2023-12-16 11:42:51 UTC
I own a Wacom Tablet One 12 which is supported by libwacom. $ lsusb # From kernel 6.5 Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 004: ID 056a:03cf Wacom Co., Ltd Wacom Billboard Bus 003 Device 003: ID 056a:03ce Wacom Co., Ltd Wacom One pen display 11.6" Bus 003 Device 002: ID 056a:03cd Wacom Co., Ltd WACOM One 12 HUB With kernel 6.6 hitting Factory, the tablet works as a display (it has an integrated display) but it is no longer detected by libwacom-tools and does nto function as a tablet. dmesg only reports, when plugging it in, [ 3.081943] usb usb4: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 6.05 [ 3.081949] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1 and lsusb, unlike the output above, only shows a USB hub. When downgrading to the latest 6.5 kernel, the tablet is fully functional again. My tests were carried under Wayland (Plasma), but I assume the issue will be on X11 as well, as the issue seems at a lower level. Hardware information: Lenovo Thinkpad X470 The tablet is connected with a single USB cable through the Thunderbolt port. I will test later with the three-way cable Wacom supplies (with an external power supply).
Could you give hwinfo outputs from both working (6.5.x) and non-working (6.6.x) kernels, as well as dmesg outputs from them? Please use attachments on Bugzilla.
Created attachment 870949 [details] dmesg under kernel 6.5 (since boot)
Created attachment 870950 [details] hwinfo under kernel 6.5
Created attachment 870951 [details] dmesg under kernel 6.6 (since boot)
Created attachment 870952 [details] hwinfo under kernel 6.6 I also ran a test on a different machine, but which uses the 3-way cable and a power supply rather than going through the Thunderbolt port (and no external power) like on this laptop, and the behavior does *not* occur.
Thanks, so it looks like a typical issue via Thunderbolt port. Tossed to Oliver, who has a better clue.
(In reply to Luca Beltrame from comment #5) > Created attachment 870952 [details] > hwinfo under kernel 6.6 > > I also ran a test on a different machine, but which uses the 3-way cable and > a power supply rather than going through the Thunderbolt port (and no > external power) like on this laptop, and the behavior does *not* occur. Please provide dmesg and hwinfo from the machine it works on with the other cable.
Created attachment 871008 [details] dmesg under kernel 6.6 (since boot) - working machine
Created attachment 871009 [details] hwinfo under kernel 6.6 (working machine)
Ok, I think it is something about supplying power via Thunderbolt. If I attach a power supply to the second USB-C port of this tablet, it works instantly - and more than that, unplugging the PSU maintains functionality until it is switched off.