[Bug 103497] New: Inverted touchpad coasting possibly caused by desktop effects

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=103497

            Bug ID: 103497
           Summary: Inverted touchpad coasting possibly caused by desktop
                    effects
           Product: DRI
           Version: XOrg git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: gabriele.mzt at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 135142
  --> https://bugs.freedesktop.org/attachment.cgi?id=135142&action=edit
dmesg since boot with drm.debug=0x06

Hi,

I noticed that the touchpad coasting has been acting really strange at random
with the current release candidates of 4.14, with rc6 being the last I tested.
Everything is fine with 4.13 or older releases.

After a bit of experimenting it seems that whenever my desktop environment
shows an on screen display, touchpad coasting happens in the wrong direction:
if I'm scrolling up, the window scrolls down. I can upload a video showing the
problem if needed. I think the problem is caused by some desktop effect that is
used for OSDs since I think I've observed the same behavior even when no OSD
was displayed. In addition to that, disabling desktop effects gets rid of the
problem.

Interestingly I observed this behavior only with QT applications.

This has never happened with 4.13, so I did a bisection and found the change
that's causing this behavior:

commit dc911f5bd8aacfcf8aabd5c26c88e04c837a938e
Author: Jim Bride <jim.bride at linux.intel.com>
Date:   Wed Aug 9 12:48:53 2017 -0700

    drm/i915/edp: Allow alternate fixed mode for eDP if available.

I confirm that reverting this change fixes the problem on v4.14-rc6. This could
really be a bug in some userspace component that it's being triggered by that
change, but it has never happened until now, so I'm reporting this here.

I built xf86-video-intel from master
(4798e18b2b2c8b0a05dc967e6140fd9962bc1a73), but the problem persists.

I'm using Debian sid and xserver 1.19.5 on a Dell XPS 13 9333 (i7-4500U with HD
Graphics 4400).


Gabriele

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