Consistent handling of USB device buttons

Alex Dubov oakad at
Sun Aug 19 22:12:59 PDT 2012


Sorry for my previous mis-posting, there appears to be some problem with gmane

There exist considerable number of hot-pluggable USB devices with helper buttons
(cameras and headsets being the more prominent examples). The buttons in
question are recognized by evdev as USB HID interfaces, so in theory they are
considered as "supported".

In practice, however, there are 2 common problems:

1. Buttons have session global effect and there's no easy, nor stable way to
limit their effect to a particular device.

2. Sometimes device buttons are recognized as "mice", rather than "keyboards"
and there's no much one can do with "mouse" buttons out of Xorg box (assorted
third party programs of varying breed and maintenance status notwithstanding).

I tried to make some sense of the issue for myself, but it appears to be
impossible to get through untold scores of various user complains on the
inter-webs. :-)

Can somebody point me at an information or discussions regarding the issues
above? After all, those devices are abundant and appear to work just fine even
on older windows xp, without any extraneous effort.

It seems logical to me that USB buttons must represent a whole input device
class on their own, with appropriate events defined. I suppose, it won't be a
big deal to incorporate support for them into existing applications, because the
need for such arrangement is long and widely recognized by anybody who tried to
rely on such buttons on Linux.


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