Libinput

Resources

libinput is [[Article description::an input device driver for Wayland compositors and X.org window system.]] It is Gentoo Linux's default input device driver.

libinput provides device detection, device handling, input device event processing and abstraction to minimize the amount of custom input code compositors need to provide the common set of functionality that users expect.^[1]

Installation

Kernel

Support for Event interface (CONFIG_INPUT_EVDEV) needs to be enabled in the kernel:

KERNEL Enabling Event interface in the kernel

Device Drivers --->
  Input device support --->
  <*>  Event interface

USE flags

USE flags for dev-libs/libinput Library to handle input devices in Wayland

`doc`	Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
`test`	Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)

Data provided by the Gentoo Package Database · Last update: 2021-03-02 16:51 More information about USE flags

Additional software

In order to enable actions gestures on the touchpad using the libinput driver, follow the install notes from the official project page on GitHub.

Remember to install the required dependencies:

root #emerge --ask x11-misc/xdotool x11-misc/wmctrl

Configuration

Xorg

Some packages are aware of the input_devices_libinput USE flag. It should already be set as the default input device driver by the make.defaults file.

To check if it is presently activated, run:

user $portageq envvar INPUT_DEVICES

If not, add it to the INPUT_DEVICES variable:

FILE /etc/portage/make.confSet INPUT_DEVICES

<syntaxhighlight lang="bash">INPUT_DEVICES="libinput"</syntaxhighlight>

After setting the INPUT_DEVICES variable remember to update the system using the following command so the changes take effect:

root #emerge --ask --changed-use --deep @world

After the update the packages dev-libs/libinput and x11-drivers/xf86-input-libinput should be installed.

By default, when libinput is the only available input driver for Xorg, no additional configuration is needed. Simply (re)start the graphical environment for the changes to take effect.

If multiple input drivers are available on the system (x11-drivers/xf86-input-evdev and x11-drivers/xf86-input-synaptics for example), then additional configuration is required.

Selecting libinput

When multiple drivers are available on the system, Xorg must be instructed to use libinput before trying to use other input drivers. This can be simply performed by symlinking the 40-libinput.conf file into the /etc/X11/xorg.conf.d/ directory:

root #ln -s /usr/share/X11/xorg.conf.d/40-libinput.conf /etc/X11/xorg.conf.d/

If the 40-libinput.conf will be edited, it is better to copy the file to the configuration directory:

root #cp /usr/share/X11/xorg.conf.d/40-libinput.conf /etc/X11/xorg.conf.d/

Xorg gives priority to the files in the /etc/X11/xorg.conf.d/ directory.

(Re)start the graphical environment for the changes to take effect.

Touchpad tap-to-click

Many users will desire the native 'tap-to-click" behavior for laptops with modern touchpads. Add the following Option lines to Xorg's libinput configuration section:

FILE /etc/X11/xorg.conf.d/40-libinput.confAdding tap-to-click

<syntaxhighlight lang="xorg.conf">Section "InputClass"
     Identifier "libinput touchpad catchall"
     MatchIsTouchpad "on"
     MatchDevicePath "/dev/input/event*"
     Option "Tapping" "True"
     Option "TappingDrag" "True"
     Driver "libinput"
EndSection</syntaxhighlight>

Touchpad natural scrolling

Natural scrolling (swipe up on touchpad - content goes up and scrollbar goes down) can be achieved by adding the following options to the /etc/X11/xorg.conf.d/40-libinput.conf file:

FILE /etc/X11/xorg.conf.d/40-libinput.confAdding natural scrolling

<syntaxhighlight lang="xorg.conf">Section "InputClass"
     Identifier "libinput touchpad catchall"
     MatchIsTouchpad "on"
     MatchDevicePath "/dev/input/event*"
     Option "NaturalScrolling" "True"
     Driver "libinput"
EndSection</syntaxhighlight>

Of course, multiple options can be combined without needing to create a new Section each time.

Pointer acceleration

A permanent reduction of pointer acceleration:

FILE /etc/X11/xorg.conf.d/40-libinput.confSetting acceleration to 90%

<syntaxhighlight lang="xorg.conf">Section "InputClass"
        Identifier "libinput pointer catchall"
        MatchIsPointer "on"
        Driver "libinput"
        Option "TransformationMatrix" "0.90 0 0 0 0.90 0 0 0 1"
EndSection</syntaxhighlight>

It is also possible to disable the acceleration completely:

FILE /etc/X11/xorg.conf.d/50-touchpad.confDisabling acceleration on touchpad

<syntaxhighlight lang="xorg.conf">Section "InputClass"
        Identifier "Thinkpad TouchPad"
        # See the result of 'xinput list'
        MatchProduct "SynPS/2 Synaptics TouchPad"
        Driver "libinput"
        Option "AccelProfile" "flat"
EndSection</syntaxhighlight>

More information under xorg.conf manual page.

The corresponding real-time test can be done using xinput. For example, for a Logitech G300s mouse :

user $xinput list

Virtual core pointer                    	id=2	[master pointer  (3)]
    ↳ Logitech G300s Optical Gaming Mouse     	id=10	[slave  pointer  (2)]

user $xinput list-props 10

Device 'Logitech G300s Optical Gaming Mouse':
	Coordinate Transformation Matrix (155):	1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000

user $xinput set-prop 10 155 0.90 0 0 0 0.90 0 0 0 1

Invocation

To list the available input devices:

root #libinput list-devices

For detailed information see the libinput-list-devices(1) man page.

root #libinput debug-events

Further invocations need dev-python/python-libevdev installed:^[2]

user $libinput replay

Error: No module named 'libevdev'
One or more python modules are missing. Please install those modules and re-run this tool.

More details man 1 libinput-replay

user $libinput measure

Usage: libinput measure [--help] <feature> [/dev/input/event0]

More details man 1 libinput-measure

Troubleshooting

Removing another input driver from INPUT_DEVICES does not prevent Xorg from loading it

This issue can occur in a variety of situations, but it is most prominent when migrating from evdev to libinput.

Be sure the x11-drivers/xf86-input-evdev package is no longer installed on the system. If /usr/share/X11/xorg.conf.d/10-evdev.conf exists then Xorg will still reference it.

Verify the evdev driver is no longer referenced anywhere by Portage (check make.conf and package.use), then depclean the system:

root #emerge --ask --depclean

Gnome overriding touchpad settings after system upgrade

As per this stack exchange post, recent versions (> 3.30.2 confirmed) of gnome override trackpad/touchpad options in X.org configuration. This can for instance cause right-click to stop working. These settings are not visible in the usual settings menu - you need to use gnome-tweak-tool and look under 'Keyboard & Mouse' to change default behavior.

External resources

References

This article is issued from Gentoo. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[1] ttps://freedesktop.org/wiki/Software/libinput/

[2] ug #703800