Re: mousedev patch

[Charles D. <cd...@mv...>]

On Mon, Jul 30, 2001 at 09:19:53AM +0200, Vojtech Pavlik wrote:
> On Sun, Jul 29, 2001 at 06:20:55PM -0700, Charles Duffy wrote:
> > This will be less acute when a single interface is available which
> > provides applications with all available information (such as
> > James's suggestion of an evdev mixer which adds a field giving the
> > minor number of the evdev device correspending with the source).
>=20
> Do we really need an evdev mixer? Isn't it easier to just try to
> open and read all the evdev devices?

No, it isn't.

There's quite a bit of software written (Qt/E, for one; Microwindows,
for another) which already has a mouse-handling architecture which
allows the mouse driver to open() a file, which is then returned by
the driver; the framework select()s on that file (among other things),
and calls the mouse event handler when select returns with the
appropriate fd.

Writing evdev drivers for this software would mean not only writing a
new driver module (a trivial task) but rearchitecting the framework to
allow drivers to own (and pass to the core) multiple fds, and
attempting to get these patches accepted by each of the projects in
question.

Furthermore, there's no means of detecting disconnection/reconnection
-- another thing that an extended evdev mixer could (and, IMHO,
/should/) report. Assuming that all evdev devices support USB is
faulty -- I personally have some that aren't (including some
non-hot-pluggable devices which may be rmmod'd on entry to powersaving
mode and re-insmod'd on restart; it's quite unuseful if applications
can't detect new minor numbers and such as a result of such things).