[Wayland-bugs] [Bug 105850] Clickpad drag lock sometimes activates

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=105850

Peter Hutterer <peter.hutterer at who-t.net> changed:

           What    |Removed                     |Added
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                 CC|                            |peter.hutterer at who-t.net

--- Comment #1 from Peter Hutterer <peter.hutterer at who-t.net> ---
The problem is this sequence:

E: 1.849800 0001 0110 0001      # EV_KEY / BTN_LEFT             1
E: 1.849800 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +695ms

read: clickpad is physically down

E: 1.866110 0003 0039 7325      # EV_ABS / ABS_MT_TRACKING_ID   7325
E: 1.866110 0003 0035 1672      # EV_ABS / ABS_MT_POSITION_X    1672
E: 1.866110 0003 0036 2028      # EV_ABS / ABS_MT_POSITION_Y    2028
E: 1.866110 0003 003a 0040      # EV_ABS / ABS_MT_PRESSURE      40
E: 1.866110 0003 0030 0000      # EV_ABS / ABS_MT_TOUCH_MAJOR   0
E: 1.866110 0003 0031 0000      # EV_ABS / ABS_MT_TOUCH_MINOR   0
E: 1.866110 0001 014a 0001      # EV_KEY / BTN_TOUCH            1
E: 1.866110 0001 0145 0001      # EV_KEY / BTN_TOOL_FINGER      1
E: 1.866110 0003 0000 1672      # EV_ABS / ABS_X                1672
E: 1.866110 0003 0001 2028      # EV_ABS / ABS_Y                2028
E: 1.866110 0003 0018 0040      # EV_ABS / ABS_PRESSURE         40
E: 1.866110 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +17ms
E: 1.878489 0003 003a 0045      # EV_ABS / ABS_MT_PRESSURE      45
E: 1.878489 0003 0018 0045      # EV_ABS / ABS_PRESSURE         45
E: 1.878489 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +12ms

read: a finger is down in position x/y with pressure

E: 1.950450 0003 0039 -001      # EV_ABS / ABS_MT_TRACKING_ID   -1
E: 1.950450 0001 014a 0000      # EV_KEY / BTN_TOUCH            0
E: 1.950450 0001 0145 0000      # EV_KEY / BTN_TOOL_FINGER      0
E: 1.950450 0003 0018 0000      # EV_ABS / ABS_PRESSURE         0
E: 1.950450 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +72ms

read: finger is up again, no finger is on the touchpad.

E: 3.679061 0003 0039 7326      # EV_ABS / ABS_MT_TRACKING_ID   7326
E: 3.679061 0003 0035 1925      # EV_ABS / ABS_MT_POSITION_X    1925
E: 3.679061 0003 0036 1593      # EV_ABS / ABS_MT_POSITION_Y    1593
E: 3.679061 0003 003a 0048      # EV_ABS / ABS_MT_PRESSURE      48
E: 3.679061 0001 014a 0001      # EV_KEY / BTN_TOUCH            1
E: 3.679061 0001 0145 0001      # EV_KEY / BTN_TOOL_FINGER      1
E: 3.679061 0003 0000 1925      # EV_ABS / ABS_X                1925
E: 3.679061 0003 0001 1593      # EV_ABS / ABS_Y                1593
E: 3.679061 0003 0018 0048      # EV_ABS / ABS_PRESSURE         48
E: 3.679061 0000 0000 0000      # ------------ SYN_REPORT (0) ----------
+1729ms

read: a finger is down again, 1.7 seconds later

So the touchpad device detects a physical click before a finger is down and
keeps that click down even though no finger is down on the touchpad. This is a
hw problem, i think your clickpad is simply wearing out. You could probably
test this by clicking the touchpad with a pen (something that doesn't get
detected by the touchpad) and see if that triggers the BTN_LEFT up event.

This isn't easy to detect, on most clickpads it is possible to trigger a click
without a finger being registered (especially on the bottom edge where it's
common to click). so we have code to accommodate for that situation, see commit
bfe05ed4a679ae2a5e3ff3b6882cbb3d046baec2.

There's an argument that we *could* release the button when the last finger is
released, but we haven't seen this case in 4 years and I'm quite loathe to add
a hack for something that looks like failing hardware.

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