[PATCH evdev] Export device node as property.

[Peter Korsgaard]

>>>>> "Peter" == Peter Hutterer <peter.hutterer at who-t.net> writes:

Hi Peter,

Thanks for picking this up again, I unfortunately have been busy with
other things ..

 Peter> There is currently no mapping between XI devices and physical
 Peter> devices other than what can be extracted by parsing the Xorg
 Peter> logfile. Add new property "Device Node" to the driver to export
 Peter> the open device file.

 Peter> The client is responsible for detecting if the device is on the
 Peter> same host and converting the data into a more useful format
 Peter> (e.g. sysfs path).

 Peter> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
 Peter> ---

 Peter> Got poked again for this at LCA. turns out what I asked Peter to
 Peter> do ages ago isn't actually feasable. I wanted this to be in the
 Peter> server so the drivers can share this property without
 Peter> re-implementation everywhere. Now, this doesn't work as the
 Peter> server can read the 'Option "Device"' value but there's no
 Peter> guarantee that the content of that is actually the device patch.
 Peter> e.g. synaptics may use "auto-dev".

 Peter> So here's a re-implementation that simply sets the property to
 Peter> the device path the driver opened. Everything else is up to the
 Peter> client, it's quite simple to get the sysfs path from the device
 Peter> node (about 5 lines with libudev).

I obviously like the concept, but this assumption basically breaks
remote X. What I think we really need is a unique identifier for XI
devices (to be able to reapply properties at next login), and with
hotplugging, the device node isn't really a good choice.

For evdev I still think our best bet for a unique identifier is
EVIOCGPHYS, like I did back then:

http://peter.korsgaard.com/patches/xorg/evdev-add-phys-property-EVIOCGPHYS-as-stable-identifer-v2.patch

E.G. use something like usb-0000:00:1d.1-1/input0 rather than
/dev/input/event14.

-- 
Bye, Peter Korsgaard