Commits on Jan 4, 2024

1. Backport: HID: wacom: Correct behavior when processing some confidenc… …

   …e == false touches
   
   There appear to be a few different ways that Wacom devices can deal with
   confidence:
   
     1. If the device looses confidence in a touch, it will first clear
        the tipswitch flag in one report, and then clear the confidence
        flag in a second report. This behavior is used by e.g. DTH-2452.
   
     2. If the device looses confidence in a touch, it will clear both
        the tipswitch and confidence flags within the same report. This
        behavior is used by some AES devices.
   
     3. If the device looses confidence in a touch, it will clear *only*
        the confidence bit. The tipswitch bit will remain set so long as
        the touch is tracked. This behavior may be used in future devices.
   
   The driver does not currently handle situation 3 properly. Touches that
   loose confidence will remain "in prox" and essentially frozen in place
   until the tipswitch bit is finally cleared. Not only does this result
   in userspace seeing a stuck touch, but it also prevents pen arbitration
   from working properly (the pen won't send events until all touches are
   up, but we don't currently process events from non-confident touches).
   
   This commit centralizes the checking of the confidence bit in the
   wacom_wac_finger_slot() function and has 'prox' depend on it. In the
   case where situation 3 is encountered, the treat the touch as though
   it was removed, allowing both userspace and the pen arbitration to
   act normally.
   
   Signed-off-by: Tatsunosuke Tobita <[email protected]>
   Signed-off-by: Ping Cheng <[email protected]>
   Signed-off-by: Jason Gerecke <[email protected]>
   Fixes: 7fb0413baa7f ("HID: wacom: Use "Confidence" flag to prevent reporting invalid contacts")
   Cc: [email protected]
   Signed-off-by: Jiri Kosina <[email protected]>
   Link: https://lore.kernel.org/all/[email protected]/
   [[email protected]: Imported into input-wacom (502296030ec6)]
   Signed-off-by: Tatsunosuke Tobita <[email protected]>
   [[email protected]: Backported into input-wacom (ab32e0b)]
   Signed-off-by: Tatsunosuke Tobita <[email protected]>

   

   flying-elephant authored Jan 4, 2024
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