libinput: disabling touchpad motion without disabling scrolling?

[Peter Hutterer]

On Sat, Jan 31, 2015 at 03:12:09PM -0800, Josh Triplett wrote:
> Is it possible to disable touchpad motion events without disabling
> scrolling?
> 
> On a laptop with both a touchstick and a touchpad, I'd like to use a
> touchpad as a scroll wheel, but not have it generate any motion events.
> 
> (Bonus if I could then scroll with one finger rather than a two-finger
> gesture, but that's much less critical.)
> 
> If this isn't currently possible, I'd be interested in working on a
> patch to fix that.  What would be the most sensible way to integrate
> that into libinput's architecture?

first a heads-up: not a big fan of this. It's a rather unusual use-case
that'll complicate the bits around it (and the touchpad code is complicated
enough as it is).

The main question as usual is _why_ do you need this particular feature and
why isn't it enough to rely on the current palm detection code? A lot of
similar requests come because synaptics' palm detection is nonexistent so
you end up having to work around the touchpad. I don't think this is the
case in libinput or at least if it is we can try to improve the palm
detection.

Cheers,
   Peter