On Fri, Feb 04, 2011 at 06:04:29AM -0800, Dan Nicholson wrote: > On Fri, Feb 4, 2011 at 5:17 AM, Peter Korsgaard <jac...@sunsite.dk> wrote: > >>>>>> "Peter" == Peter Hutterer <peter.hutte...@who-t.net> writes: > > > > Hi, > > > > >> 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. > > > > Peter> the reasons why I chose the device node (after some feedback > > Peter> from Lennart) > > > > Peter> were: > > > > Peter> - the device node is the only reliable identifier we have in the > > Peter> driver. on any system, irregardless of the platform, the device > > Peter> node will be avaible. > > > > Also on Windows / Cygwin? > > > > Peter> - the device node can be tracked back to the configuration > > Peter> backend and the configuration. I configure devices in the > > Peter> xorg.conf with /dev/input/eventX, not through the phys. > > > > True. But most people presumably don't hand edit xorg.conf, but rather > > use gnome-mouse-preferences or whatever. > > > > The question is perhaps what the use case for this property is? To > > easily figure out what xinput id corresponds to a config entry in > > xorg.conf? The reason I wanted the property was slightly different. As > > the xinput ids are not stable, I wanted a stable identifier so I can > > reapply xinput settings at login time (E.G. for the coordinate > > transformation matrix for multihead touchscreens) through > > gnome-settings-daemon, similar to how it does for the xrandr setup. > > Maybe another property is needed to satisfy that. What about "Device > UID", which is string setup by the driver. On evdev, it uses > EVIOCGPHYS, but it's up to the driver since it has the most details > about the device. I still think "Device Node" is useful, but I see > your point about needing a unique identifier. Then > gnome-settings-daemon can look at the combination of DISPLAY hostname > and "Device UID" to know which cached settings to grab.
Ok, I missed that we're trying to solve two different use-cases. Punting a unique device ID into the properties is be quite useful, I've been struggling for a while with figuring out how to make per-device configuration work in a sane manner. However, is the phys path enough here? Users think in physical devices and we should (if we can) allow for the same device being plugged into a different port. Cheers, Peter _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
