bug#35450: Libinput touchpad driver not taking precedence over synaptics

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

On Sat, Apr 27, 2019 at 05:19:16PM +0200, pelzflorian (Florian Pelz) wrote:
> On my Macbook the buggy synaptics driver gets used.  The definition of
> %default-xorg-modules indicates libinputs is meant to be the default.
> […]

Apparently the reason synaptics is preferred over libinput upstream is
that upstream does not expect users to install the synaptics driver
(or wacom driver) unless they have trouble with libinput.

https://gitlab.freedesktop.org/xorg/driver/xf86-input-libinput has:
> commit 59e5db025307404fbfbc82f2fb3fe91d6a3005d7
> Author: Stefan Dirsch <sndirsch@suse.de>
> Date:   Thu May 19 17:35:57 2016 +0200
> 
>     conf: rename to 70-synaptics.conf
>     
>     Bump up the synaptics driver to 70, so it get's preferred over libinput, which
>     was dropped down to 60. The synaptics driver is more of a leaf package
>     than libinput (which covers a multitude of device types) and can be removed by
>     default. When specifically installed by the user, the synaptics driver should
>     override the system default.
>     
>     Similar to what was done for wacom configuration file.
>     
>     https://bugzilla.suse.com/show_bug.cgi?id=979554
>     
>     Signed-off-by: Stefan Dirsch <sndirsch@suse.de>
>     Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

https://gitlab.freedesktop.org/xorg/driver/xf86-input-synaptics has:
> commit 0f7c5ed02d4f2de34c6fb1fc3f4debceef08d0d7
> Author: Peter Hutterer <peter.hutterer@who-t.net>
> Date:   Tue Aug 30 12:42:58 2016 +1000
> 
>     conf: drop libinput to below the other drivers
>     
>     This is the continuation of 3f569ec493e, dropping libinput below the remaining
>     drivers. Wacom and synaptics already sort higher anyway (see wacom commit
>     0da5cd54 and synaptics commit 59e5db025). evdev remains the catchall
>     basic fallback driver and is overwritten by libinput. The two drivers affected
>     by this patch are joystick and vmmouse.
>     
>     joystick is a niche driver and drives devices libinput doesn't handle anyway
>     so there is no need to override. If a user installs it, presumably it is to
>     use it.
>     
>     vmmouse is a niche driver and does not assign itself anymore for newer kernel
>     drivers (see vmmouse commit 576e8123 from Oct 2014). So if vmmouse is
>     installed it can safely sort higher than libinput.
>     
>     Note: this is upstream behavior, distributions have to work out the wanted
>     behavior themselves by renaming the config snippets accordingly.
>     
>     Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
>     Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Therefore the best course of action might be to remove synaptics from
Guix’ defaults for xorg.conf.d instead of changing the numbering.

Regards,
Florian