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| author | Peter Hutterer <peter.hutterer@who-t.net> | 2020-08-26 11:59:47 +1000 |
|---|---|---|
| committer | Peter Hutterer <peter.hutterer@who-t.net> | 2020-10-07 08:14:21 +1000 |
| commit | c856f26dd77e5b0b5fd3862e572be456629de943 (patch) | |
| tree | 3a9cf95fbbec352f79116d7b3b948aaa56a6c0e9 | |
| parent | 2e5e74c0bc7dc62831ed2d10ea1028abed37b382 (diff) | |
| download | libinput-c856f26dd77e5b0b5fd3862e572be456629de943.tar.gz | |
touchpad: ignore the ALPS jump to 4095/0
Some ALPS touchpad send the occasional 4095/0 event on slot 1 during
two-finger interaction before snapping back to the actual position of the
finger. There doesn't seem to be a specific heuristic to predict this so let's
hardcode those values. When detected, overwrite the current touch point with
the position of the last point. This will likely cause a small pointer jump
when the finger later moves to the real position but based on #492 this could
be a second later, so all bets are off anyway.
Fixes https://gitlab.freedesktop.org/libinput/libinput/-/issues/492
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit 0c5112155600629fc6ac8d927d66118554180ecc)
| -rw-r--r-- | doc/user/touchpad-jumping-cursors.rst | 14 | ||||
| -rw-r--r-- | src/evdev-mt-touchpad.c | 13 |
2 files changed, 27 insertions, 0 deletions
diff --git a/doc/user/touchpad-jumping-cursors.rst b/doc/user/touchpad-jumping-cursors.rst index f1c49d74..e1b065a1 100644 --- a/doc/user/touchpad-jumping-cursors.rst +++ b/doc/user/touchpad-jumping-cursors.rst @@ -64,3 +64,17 @@ See :ref:`reporting_bugs` for more details. Note that it most cases, libinput cannot actually fix the issue. Filing a bug is useful to figure out if there are other factors at play or whether there are heuristics we can employ to reduce the impact. + +------------------------------------------------------------------------------ +AlpsPS/2 ALPS DualPoint TouchPad jumping to 4095/0 +------------------------------------------------------------------------------ + +A special case of pointer jumps happens on ``AlpsPS/2 ALPS DualPoint TouchPad`` +devices found in the Lenovo ThinkPad E465 and E550 and likely others with +the same touchpad hardware. On those devices, the touchpad occasionally +sends an event for the second finger to move to position 4095/0 before +moving back to the original position. libinput detects this movement and +removes it but depending on the interaction this may cause a smaller jump +later when the coordinates reset to the new position of the finger. + +Some more information is available in `Gitlab Issue #492 <https://gitlab.freedesktop.org/libinput/libinput/-/issues/492>`__. diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c index 9bee7606..4064a8ea 100644 --- a/src/evdev-mt-touchpad.c +++ b/src/evdev-mt-touchpad.c @@ -1542,6 +1542,19 @@ tp_detect_jumps(const struct tp_dispatch *tp, abs_distance = hypot(mm.x, mm.y) * reference_interval/tdelta; rel_distance = abs_distance - t->jumps.last_delta_mm; + /* Special case for the ALPS devices in the Lenovo ThinkPad E465, + * E550. These devices send occasional 4095/0 events on two fingers + * before snapping back to the correct position. + * https://gitlab.freedesktop.org/libinput/libinput/-/issues/492 + * The specific values are hardcoded here, if this ever happens on + * any other device we can make it absmax/absmin instead. + */ + if (tp->device->model_flags & EVDEV_MODEL_ALPS_SERIAL_TOUCHPAD && + t->point.x == 4095 && t->point.y == 0) { + t->point = last->point; + return true; + } + /* Cursor jump if: * - current single-event delta is >20mm, or * - we increased the delta by over 7mm within a 12ms frame. |