Created attachment 127705 [details] two-finger scroll up There is a very noticeable delay between start of two-finger movement and an actual scroll event. This doesn't happen on X11 with synaptics driver. I'm using Lenovo Thinkpad T440 (OS: Arch, Gnome/Wayland, libinput version: 1.5.0-1). Attachment is evemu recording in which i place two fingers and move up. ###### udevadm info /sys/class/input/event13 ###### P: /devices/platform/i8042/serio1/input/input13/event13 N: input/event13 E: DEVNAME=/dev/input/event13 E: DEVPATH=/devices/platform/i8042/serio1/input/input13/event13 E: ID_BUS=i8042 E: ID_INPUT=1 E: ID_INPUT_HEIGHT_MM=66 E: ID_INPUT_TOUCHPAD=1 E: ID_INPUT_TOUCHPAD_INTEGRATION=internal E: ID_INPUT_WIDTH_MM=97 E: LIBINPUT_DEVICE_GROUP=11/2/7/1b1:isa0060/serio1 E: LIBINPUT_MODEL_SYNAPTICS_SERIAL_TOUCHPAD=1 E: MAJOR=13 E: MINOR=77 E: SUBSYSTEM=input E: USEC_INITIALIZED=2378449 ##### cat /sys/class/dmi/id/modalias ##### dmi:bvnLENOVO:bvrGJET84WW(2.34):bd06/22/2015:svnLENOVO:pn20B6005JUS:pvrThinkPadT440:rvnLENOVO:rn20B6005JUS:rvr0B98401PRO:cvnLENOVO:ct10:cvrNotAvailable: ##### physical touchpad dimensions ##### 100x70 mm
How big do you think the delay is? in mm or time?
Feels like it's around 5-7mm.
try the hwdb entry here: https://github.com/systemd/systemd/pull/4149 I have the same laptop (T440s, same touchpad hardware) with this applied and the scroll delay is the intended 2mm only
I tried out the entry you provided as well as the one generated by touchpad-edge-detector. Cursor speed is bit different but there is still scroll delay compared to synaptics. It feels not as sensitive to small swipes.
Is it possible that this problem is related to gnome? I just tried plasma under wayland and the issue is gone (even cursor movement feels kinda smoother).
shouldn't be different, it's libinput that decides when scrolling kicks in. the only difference could be if gnome doesn't immediately forward the scroll events. grab libinput from git://git.freedesktop.org/git/wayland/libinput and build it with the gtk3-devel package installed. That gives you ./tools/event-gui. Run that as root and scroll. This tool takes events straight from libinput, so if you see the two green bars moving as expected, then the delay really is in gnome somewhere.
Yup, it's definitely somewhere in gnome. Test application responds to scroll immediately.
ok. I think we should close this bug now, looks like comment #3 fixes the underlying issue and for the GNOME bug please file one against mutter. Bonus points for pasting the bug link in here afterwards ;)
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