xinput ids

[Peter Hutterer]

On Tue, Jun 09, 2015 at 07:23:36AM +0200, Peter Korsgaard wrote:
> >>>>> "Peter" == Peter Hutterer <peter.hutterer at who-t.net> writes:
> 
> Hi,
> 
> >> To find the ID reliably. Is this the right way to do it? Is there
>  >> perhaps a better way with udev/systemd?
> 
>  > what do you use for configuring and why do you need the ID specifically? if
>  > you use xinput to configure things, you can use the device name as well.
> 
>  > xinput set-prop "some device name" "some property name" 1 2 3
> 
> A typical use case is to set the coordinate transformation matrix for
> touchscreens in multihead setups.
> 
> In the likely situation that the touchscreens are of the same type they
> will have the same device name, so you need to fish out the
> corresponding /dev/input/event* device node and pass it to udevadm info
> (assuming that the server is local) to E.G. key off the ID_PATH
> (E.G. the USB port the touchscreen is connected to).

yeah, fair enough but that's not what I suspected from the original message
(Kai only talks of a single device, afaict).

related question for this case though: would xinput get-id call be
interesting then? e.g. for two touchscreens you'd get
$ xinput get-id "touchscreen"
12 16 

Cheers,
   Peter