From: Dmitry Torokhov <dtor_core@ameritech.net>
To: Aaron Lehmann <aaronl@vitelus.com>
Subject: Re: Synaptics touchpad + external mouse with Linux 2.6?
Date: Tue, 23 Mar 2004 01:00:37 -0500
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Cc: linux-kernel@vger.kernel.org, Joshua Kwan <joshk@triplehelix.org>
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On Tuesday 23 March 2004 12:40 am, Aaron Lehmann wrote:
> On Mon, Mar 22, 2004 at 11:32:29PM -0500, Dmitry Torokhov wrote:
> > Because it is not implementation, it is hardware limitation. Synaptics native
> > protocol uses 6 bytes, standard PS/2 3 or 4. The protocols are not compatible
> > at all so unless the PC has an active multiplexing controller (which provides
> > up to 4 completely independent AUX ports) all devices have to speak the same
> > protocol. 
> 
> This only matters if you plug in a PS/2 mouse. If you have a USB
> mouse, that's another issue entirely. Ideally XFree86 should read
> /dev/input/mice and not have to worry about the specifics of the
> device.

You can do that if you do not care about extended features, just use
/dev/input/mice and all should be fine (well, for tapping to work you will
have to pass psmouse.proto as in-kernel synaptics->PS/2 protocol emulation
does not process taps).

> When you use the synaptics driver, XFree86 won't accept input 
> from USB mice. It may be possible to work around this by using
> multiple Input sections, 

That is correct. You should use one input section for devices speaking
PS/2 protocol and other input sections for devices using other protocols.

>                           but that seems especially awkward when 
> Synaptics events are presented in both /dev/input/mice and /dev/psaux.

Well, that is not a surprise as /dev/input/mice is a synonim for /dev/psaux
in 2.6. If you have your XFree reading from both devices you will get
duplicate events no matter what hardware it is (USB, PS/2, Synaptics).
Now, default XFree86 Synaptics setup has "auto-dev" protocol and "/dev/psaux"
device, but with "auto-dev" protocol the driver actually scans
/dev/input/eventX devices for Synaptics and /dev/psaux is only used as a
fall-back so the same setup works in 2.4.

> 
> I recently switched from the synaptics driver reading /dev/psaux to
> the generic ImPS/2 driver reading /dev/input/mice. (Note that the only
> reason I ever installed the synaptics driver was that a kernel upgrade
> forced me to.) It performs bearably, but I personally wish that I
> could click by tapping and use the odd scrolling button as button3
> (this only works when I hit the button exactly in the middle). 

Try psmouse.proto=bare or psmouse.proto=imps

> At lease I can plug in external mice without hassle.

That means that your hardware does not have the problem I described in my
other mail.

-- 
Dmitry
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