[Wayland-bugs] [Bug 99975] Trackpad drags halt suddenly

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99975

--- Comment #4 from Peter Hutterer <peter.hutterer at who-t.net> ---
When you were using the synaptics driver, did you change its options for
FingerHigh or FingerLow?

here's what happens here, the touchpad is set up for a schmitt trigger with
values 30 high and 25 low, i.e. over 30 triggers a touch down, falling below 25
triggers a touch up. 

In the recording this first happens here
E: 5.600873 0003 0035 2390      # EV_ABS / ABS_MT_POSITION_X    2390
E: 5.600873 0003 003a 0024      # EV_ABS / ABS_MT_PRESSURE      24
E: 5.600873 0003 0000 2390      # EV_ABS / ABS_X                2390
E: 5.600873 0003 0018 0024      # EV_ABS / ABS_PRESSURE         24
E: 5.600873 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +12ms

and after that you don't make a pressure of 30 anymore.

Device range is 0..3276, so 2390 is 73% of the way in, so that matches your
description. The lowest pressure recording of true interaction seems to be 14.

the synaptics driver pretty disabled pressure-based touchpads for elantech
touchpads so that would explain why you're seeing a change now with libinput, I
left it intentionally. I think measuring the real finger pressure would be a
useful here, I'll see if I can produce a useful tool for this.

You can hack this up for now if you want, in libinput's tp_init_pressure()
function set tp->pressure.high and tp->pressure.low to 1. Then you can use the
touchpad normally and run evemu-record in the background for a few hours to
collect enough data.

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