[PATCH libinput] touchpad: only pair internal trackpoint devices with internal touchpads

[Peter Hutterer]

fwiw, please don't do a reply to list only, it makes it harder to track
emails.

On Wed, Apr 15, 2015 at 07:17:35AM -0700, Bill Spitzak wrote:
> On 04/14/2015 09:01 PM, Peter Hutterer wrote:
> >Internal touchpads with trackpoints are either BUS_I8042 or BUS_I2C, but not
> >BUS_USB. Lenovo sells external keyboards with a trackpoint built-in, make sure
> >we don't pair that trackpoint with the internal touchpad.
> >And likewise, the internal trackpoint should not be paired with e.g. a wacom
> >touch device.
> >
> >Lenovo had one external device that has a trackpoint and a touchpad on an
> >external keyboard. That device won't be covered with this patch, if we have a
> >user we can re-consider.
> 
> Would checking if both devices are on the same bus (rather than not on the
> USB bus) work for the systems you have, and also cover this case?
> 
> (ie. use bus_tp == bus_trp instead of tp_is_internal && trp_is_internal)
> 
> Pardon me if I have no idea what I am talking about.

nah, good call, we had that idea too. there was the faint memory of some
synaptics device that couldn't handle the trackstick on i2c and went through
ps/2, so that may have broken this approach. in the end we went with this
approach since it that covered that (though possibly obsolete) case too.

Cheers,
   Peter