PROBLEM: Regression likely in hid_uclogic driver breaks Huion Inspiroy H640 drawing tablet

[Stefan Hansson]

Hi!

Somewhere between Linux 5.17.6 and 5.18.11 the Huion tablet I have 
stopped working properly. In GNOME Control Center it is identified as 
Huion New 1060 Plus, however that's a different tablet than the one I 
have. Mine is a Huion Inspiroy H640, and it uses the hid_uclogic driver.

With Linux 5.17.6, the tablet works as expected with all the buttons 
being detected and the stylus being usable. With 5.18.11, the buttons 
work fine but the stylus does not work correctly. The first time I 
approach the tablet with the stylus it works properly, i.e., the cursor 
on my screen moves around and follows the stylus around the tablet as 
expected. It continues working like this until I remove the stylus from 
the tablet. After I remove it from the tablet, the cursor never gets 
controlled by the stylus again. I can see that the tablet detects the 
stylus (it has a small indicator light), but the cursor doesn't move 
when I approach the tablet again. To clarify, with Linux 5.17.6, the 
cursor moves around just fine when I remove and then put it back to the 
tablet, just as you would expected.

It may also be worth noting that it worked fine when I previously used 
it around six months ago, although I'm not sure what version of Linux I 
was using at that time (whatever Fedora shipped back then). I also tried 
reproducing it with yesterday's linux-next and Linux 5.19.0-RC7, and the 
behaviour was the same as 5.18.11. I am currently trying to bisect this, 
but it's not going very fast as I currently only have access to a dual 
core laptop from 2014, so building Linux takes a good while.

Regards,
Stefan Hansson