Double tap registered as single tap on Acer Aspire V5-573G touchpad

Summary

The touchpad of my laptop has no matching kernel driver and runs in a compatibility mode, simulating a PS/2 mouse.

[    2.458797] psmouse serio1: alps: Unsupported ALPS V9 touchpad: E7=73 03 c8, EC=73 04 13
[    3.069333] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input6

This simulation of a mouse seems to modify tap timings so that two successive short taps are presented to the operating system as one longer click quickly followed by a short click, which libinput seems to discard as a bounce.

Steps to reproduce

Quickly tap this touchpad model twice.

Required information

• libinput version: libinput 1.18.1-1 on Arch
• hardware information: Acer Aspire V5-573G Touchpad udevadm info
• libinput record output
• libinput debug-events --verbose output

Unfortunately, it looks like ALPS V9 is not supported in the kernel yet, the message you are seeing was added there to warn about it.

Without kernel support, it is not possible to make your touchpad fully work at the libinput level. However, we can add a quirk to disable button denouncing for your device so at least you can double click reliability.

Let's see if @whot knows a better solution for this problem, otherwise, I can put together the quirk.

Unfortunately, there's no better solution than a quirk, no. I think that we could disable debouncing via quirk for any device matching ImPS/2 Generic Wheel Mouse since no real mouse actually uses that string. That should catch most devices that are just emulated and likely to trigger that (or other bugs).

mentioned in commit JoseExposito/libinput@c36dccca

mentioned in merge request !687 (merged)

@squarewave , I opened a merge request to (hopefully) fix your touchpad issues, but I'll need your help to test it.

The easiest way to test it is to open the file /etc/libinput/local-overrides.quirks (create it if it isn't present) and copy and paste this:

[Emulated Mouse]
MatchName=ImPS/2 Generic Wheel Mouse
ModelBouncingKeys=1

Restart and let me know if it worked please.

mentioned in commit JoseExposito/libinput@c9483a6a

closed with commit c9483a6a

@JoseExposito, I can confirm the quirk fixes the issue. Thank you!

mentioned in commit Avidgamefan/libinput@031a2742