HID: multitouch: Fix Yoga Book 9 14IAH10 touchscreen misclassification

The Lenovo Yoga Book 9 14IAH10 (83KJ) (17EF:6161) firmware includes a
HID_DG_TOUCHPAD application collection designed for the Windows inbox HID
driver's Win8 PTP touchpad mode.  On Linux the HID_DG_TOUCHSCREEN
collections provide the correct direct-touch interface.  The presence of
the touchpad collection causes hid-multitouch to misclassify the
touchscreen nodes as indirect buttonpads, leaving them non-functional.

Within the touchpad collection:
- HID_UP_BUTTON usages trigger the touchscreen-with-buttons heuristic
  that sets INPUT_MT_POINTER on the touchscreen applications.
- The HID_DG_TOUCHPAD application itself sets INPUT_MT_POINTER via
  mt_allocate_application(), propagating to all touchscreen nodes.
- A HID_DG_BUTTONTYPE feature (report 0x51) returns MT_BUTTONTYPE_CLICKPAD,
  setting td->is_buttonpad = true for the entire device.

Additionally, the firmware resets if any USB control request arrives while
the CDC-ACM interface is initialising (~1.18 s after enumeration).
The Win8 compliance blob (0xff00:0xc5) and Contact Count Max feature
reports in the touchscreen collections trigger GET_REPORT calls at probe
that hit this window.  Surface Switch (0x57) and Button Switch (0x58)
feature reports are sent by mt_set_modes() on every input-device open and
close, repeatedly hitting this window throughout device lifetime.

The firmware also leaves a persistent ghost contact in its contact buffer
(contact ID 2, fixed coordinates, tip always asserted) on every enumeration.
This ghost occupies a multitouch slot and prevents KWin from seeing a clean
finger-lift, causing stuck touch state.  The ghost is cleared when Input
Mode is set via HID_REQ_SET_REPORT at probe.

Fix using a report descriptor fixup in mt_report_fixup() and a class
definition update:

1. Remove the entire HID_DG_TOUCHPAD application collection.  Parsing
   HID short items from its header to the matching End Collection and
   closing the gap with memmove eliminates all three BUTTONPAD
   heuristics and the feature reports within the collection.

2. Neutralize the Win8 compliance blob feature reports remaining in the
   touchscreen collections by changing Usage Page 0xff00 to 0x0f00,
   preventing the case 0xff0000c5 branch in mt_feature_mapping() from
   issuing GET_REPORT.

3. Neutralize the Contact Count Max feature reports by changing usage
   0x55 to 0x00; set maxcontacts = 10 in the class definition so the
   driver uses the correct contact limit without querying the device.

4. Neutralize Surface Switch (0x57) and Button Switch (0x58) feature
   report usages in the Device Configuration collection so mt_set_modes()
   does not issue HID_REQ_SET_REPORT for these on every input-device
   open/close.  Input Mode (0x52) is intentionally left intact: the single
   HID_REQ_SET_REPORT at probe flushes the firmware's contact buffer and
   clears the persistent ghost contact.  By probe time the cdc-acm driver
   has already satisfied the CDC-ACM init watchdog (~130 ms), so this
   request arrives safely after the reset window has closed.

5. Add MT_QUIRK_NOT_SEEN_MEANS_UP to the MT_CLS_YOGABOOK9I class so that
   contacts not present in a frame are released via INPUT_MT_DROP_UNUSED,
   preventing stale multitouch slots from lingering if the firmware omits
   a contact from a report.

Signed-off-by: Dave Carey <carvsdriver@gmail.com>
Tested-by: Dave Carey <carvsdriver@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

0 files changed, 0 insertions, 0 deletions