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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> | 2020-09-07 02:13:40 +0000 |
| commit | 0c5112155600629fc6ac8d927d66118554180ecc (patch) | |
| tree | 88536e70ab7ec1280714b06e94638e68ef0f0899 /doc | |
| parent | 9f8b9f5f532edcc2698e2ffca9d19bb1bf6054cc (diff) | |
| download | libinput-0c5112155600629fc6ac8d927d66118554180ecc.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>
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/user/touchpad-jumping-cursors.rst | 14 |
1 files changed, 14 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>`__. |