[PATCH xf86-input-libinput] Add tablet pad support

[Peter Hutterer]

On Fri, Apr 22, 2016 at 12:07:27PM +1000, Peter Hutterer wrote:
> > Also, on a somewhat-related note: I'm noticing that having
> > xf86-input-libinput and xf86-input-wacom installed alongside each
> > other results in some pretty annoying driver priority issues. I've got
> > 0.17.0 installed at the moment and it ends up grabbing the pad on my
> > 24HDT since udev tags it as a keyboard (probably because it has
> > KEY_PROG1 through KEY_PROG3) and since libinput's xorg.conf.d file has
> > a '90' prefix. The libinput driver later drops the device since udev
> > also tags it as a buttonset, preventing the buttons from being usable
> > under X at all (let alone usable by GNOME). If simultaneous
> > installation of the libinput and wacom drivers is supposed to work,
> > there might be some work to do...
> 
> yes, we'll have to use the new-ish NoMatch bits for that. unfortunately,
> there is little way around this and I haven't gotten to it yet. I'll bump
> this up in the todo list.

I stared at this for a bit today and our main problem is that we don't have
a release with the NoMatch* bits, so we can't ship anything in the near
future that relies on it.

I think the only reasonable solution for now is for distributions to install
50-wacom.conf as 91-wacom.conf and thus override any libinput assignments.
The wacom driver is more of a leaf package than libinput, so the simple
instructions for users would then be "if you want libinput to handle the
tablet, uninstall xf86-input-wacom".

Cheers,
   Peter