Re: master 3b41141708: Expose the name of an event's input device to Lisp

[Po Lu]

Brian Cully <bjc@spork.org> writes:

>       That would be because the only way that USB has to disambiguate
> otherwise identical devices is by serial number. You can verify this
> yourself, if you like, by looking at the output of ‘lsusb -v’. I have
> demonstrated that libinput does not use that information to name devices
> and has no apparent problem re-using the same name across multiple
> devices.

libinput is libinput.  It is a driver for the X server, but it is
otherwise completely unrelated to the X input extension, which can only
operate correctly if each name uniquely identifies a device.

>       Is libinput being used for your mice? I suspect that the
> discrepancy may arrive from different driver usage.

libinput is the device driver being used, yes.

>       So, I’d originally flashed my microcontroller because I thought
> it would be the easiest way to test things, and while I do have
> duplicate devices in my home, they’re Steam Controllers and I didn’t
> think it worth digging them out of storage for this. However, in the
> interest of using “real” devices, here’s the output of ‘libinput
> list-devices’ with them plugged in.
>
> ---[snip]---
> Device:           Valve Software Steam Controller
> Kernel:           /dev/input/event30
> Group:            4
> Seat:             seat0, default
> Capabilities:     keyboard pointer 
>       ⋮
> Device:           Valve Software Steam Controller
> Kernel:           /dev/input/event29
> Group:            5
> Seat:             seat0, default
> Capabilities:     keyboard pointer 
> ---[snip]---
>
>       They work in X just fine.

Then either the names are different, or the devices behave identically
in every way, and nobody has yet had a reason to treat the devices
differently.  If the second "Valve Software Steam Controller" was a foot
pedal, I'm certain it would not be working correctly in software
designed for that foot pedal.

Anyway, that "they work fine in X" proves this is not a problem in
practice, so we will wait until someone actually complains in real word
usage.

> Here are the logs about their mouse functionality:

Did you try asking for the device name using the xinput tool?  What does
it say?

Also, what happens if you run `xinput list-props "Valve Software Steam
Controller"'?  Can you show the output?