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<base href="https://bugs.freedesktop.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Two-finger scrolling is unreliable, hard to trigger"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101051">101051</a>
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<th>Summary</th>
<td>Two-finger scrolling is unreliable, hard to trigger
</td>
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<th>Product</th>
<td>Wayland
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>libinput
</td>
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<th>Assignee</th>
<td>wayland-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>stark3y@gmail.com
</td>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=131364" name="attach_131364" title="udev info, evemu info, xinput props">attachment 131364</a> <a href="attachment.cgi?id=131364&action=edit" title="udev info, evemu info, xinput props">[details]</a></span>
udev info, evemu info, xinput props
libinput version: 1.7.1
Device: Lenovo Thinkpad 13 "ETPS/2 Elantech Touchpad"
DMI:
dmi:bvnLENOVO:bvrR0CET27W(1.15):bd09/05/2016:svnLENOVO:pn20GJCTO1WW:pvrThinkPad13:rvnLENOVO:rn20GJCTO1WW:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
See attached udev info, evemu device description, xinput props
Hi,
Two-finger scrolling on my touchpad became very, very hard to trigger after
updating from 1.5.3-1 to 1.7.1-1 (Arch package version). My guess would be
it's related to the pressure-based touch detection introduced in 1.7.0, but
that's just a guess.
Normal, single-finger touch events work fine, it's only two finger scrolling
which doesn't. I have to press very hard and deliberately to get two finger
scrolling to trigger at all - but even trying to do that it is pretty hard to
trigger.
Before the update, two-finger scrolling was as easy to trigger as normal mouse
movement, with very light finger pressure.
I've tried to collect evemu data showing the problem. See attached three
evemu logs:
one-finger.txt:
Normal cursor movement
two-finger-noscroll.txt:
Two fingers with similar applied pressure as one-finger.txt.
Scrolling was not triggered.
In fact, usually, this results in zero libinput events being generated
(as reported by libinput-debug-events), but sometimes normal mouse movement
is triggered.
two-finger-scroll.txt:
Two fingers, on an attempt that did trigger two-finger scrolling.
The pressure is very high.
I tried tweaking the pressure settings as described here[1], but it didn't
help (and mostly made one-finger movement worse).
I've also attached plotted evemu stats (as described in [1] again), for the
same movements (20 swipes upwards) with one and two fingers. The pressure for
two fingers appears to be lower than one, and there are significantly fewer
PRESSURE events for two fingers.
Let me know if there's anything more I can provide.
[1] <a href="https://wayland.freedesktop.org/libinput/doc/latest/touchpad_pressure.html">https://wayland.freedesktop.org/libinput/doc/latest/touchpad_pressure.html</a></pre>
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