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

On Thu, Aug 4, 2022 at 8:24 PM José Expósito [off-list ref] wrote:

Hi again,

On 2022-07-26 18:48, José Expósito wrote:

quoted

The first bad commit is 87562fcd1342 ("HID: input: remove the need for
HID_QUIRK_INVERT"):
https://lore.kernel.org/all/20220203143226.4023622-11-benjamin.tissoires@redhat.com/ (local)
(CCing the folks whose email is in the patch tags)

I reverted the patch on hid/for-next and, after fixing a tiny conflict,
I can confirm that the tablet works again as expected.

I'd need to investigate a bit more over the weekend, but I think that
all HUION tablets with the latest firmware (internally, v2) are
affected.

Indeed, it looks like v2 devices are affected. Similar reports:

 - https://github.com/DIGImend/digimend-kernel-drivers/issues/626
 - https://bugzilla.kernel.org/show_bug.cgi?id=216106

Kindly sending this thread back to your inbox to see if we could fix
this regression.

[sorry, I was out on vacation the past 2 weeks and this week was the
usual "urgent" thing I have to day for yesterday]

Ideally, I'd like to not revert that commit. It solves a bunch of
issues on many devices, so that's maybe not the way forward.

FWIW, it was quite painful to tweak and that was a solution that
matches the hid-multitouch devices I could find.

I tried to process your email when you described the succession of
events without much success.

Would you mind dumping a hid-record when exposing the bug?

Cheers,
Benjamin

Best wishes,
Jose

quoted

Those tablets do not set the inrange bit (UCLOGIC_PARAMS_PEN_INRANGE_NONE).
The driver sets it and uses a timer to remove it.
See drivers/hid/hid-uclogic-core.c, function uclogic_raw_event_pen().
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