[PATCH] input: map BTN_FORWARD to button 2 in mousedev

[PATCH] input: map BTN_FORWARD to button 2 in mousedev

[Németh Márton]

From: Márton Németh <nm127@freemail.hu>

In mousedev the BTN_LEFT and BTN_FORWARD were mapped to mouse button 0, causing
that the user space program cannot distinguish between them through /dev/input/mice.
The BTN_FORWARD is currently used in the synaptics.c, logips2pp.c and in alps.c. All
mice have BTN_LEFT, but not all have BTN_MIDDLE (e.g. Clevo D410J laptop). Mapping
BTN_FORWARD to mouse button 2 makes the BTN_FORWARD button useful on the mentioned
laptop.

Signed-off-by: Márton Németh <nm127@freemail.hu>
---

The Clevo D410J laptop has "AlpsPS/2 ALPS GlidePoint" touchpad having the following
physical layout:

     +-------------------+ +-------------+ +-------------------+
     |                   | | BTN_FORWARD | |                   |
     |     BTN_LEFT      | +-------------+ |     BTN_RIGHT     |
     |                   | +-------------+ |                   |
     |                   | |  BTN_BACK   | |                   |
     +-------------------+ +-------------+ +-------------------+

This model does not have any BTN_MIDDLE, but the BTN_FORWARD could be used instead.
The following table summarizes the map changes:

     Button name  | Mapping in 2.6.19-rc3 | The changed mapping
     -------------+-----------------------+---------------------
     BTN_LEFT     |          0            |          0
     BTN_RIGHT    |          1            |          1
     BTN_FORWARD  |          0            |          2
     BTN_BACK     |          3            |          3


--- linux-2.6.19-rc4/drivers/input/mousedev.c.orig	2006-10-31 04:37:36.000000000 +0100
+++ linux-2.6.19-rc4/drivers/input/mousedev.c	2006-11-05 02:34:56.000000000 +0100
@@ -196,12 +196,12 @@ static void mousedev_key_event(struct mo
  	switch (code) {
  		case BTN_TOUCH:
  		case BTN_0:
-		case BTN_FORWARD:
  		case BTN_LEFT:		index = 0; break;
  		case BTN_STYLUS:
  		case BTN_1:
  		case BTN_RIGHT:		index = 1; break;
  		case BTN_2:
+		case BTN_FORWARD:
  		case BTN_STYLUS2:
  		case BTN_MIDDLE:	index = 2; break;
  		case BTN_3:

Re: [PATCH] input: map BTN_FORWARD to button 2 in mousedev

[Dmitry Torokhov]

On 11/5/06, Németh Márton <nm127@freemail.hu> wrote:
> From: Márton Németh <nm127@freemail.hu>
>
> In mousedev the BTN_LEFT and BTN_FORWARD were mapped to mouse button 0, causing
> that the user space program cannot distinguish between them through /dev/input/mice.
> The BTN_FORWARD is currently used in the synaptics.c, logips2pp.c and in alps.c. All
> mice have BTN_LEFT, but not all have BTN_MIDDLE (e.g. Clevo D410J laptop). Mapping
> BTN_FORWARD to mouse button 2 makes the BTN_FORWARD button useful on the mentioned
> laptop.
>

I'd rather not touch mappings in legacy mousedev driver. I believe
both synaptics and evdev X drivers will correctly recognize
BTN_FORWARD, is there any reason you are not using them?

-- 
Dmitry

Re: [PATCH] input: map BTN_FORWARD to button 2 in mousedev

[Németh Márton]

Dmitry Torokhov <dtor@insightbb.com> wrote:

> On 11/5/06, Németh Márton <nm127@freemail.hu> wrote:
> > From: Márton Németh <nm127@freemail.hu>
> >
> > In mousedev the BTN_LEFT and BTN_FORWARD were mapped to
mouse button 0, causing
> > that the user space program cannot distinguish between
them through /dev/input/mice.
> > The BTN_FORWARD is currently used in the synaptics.c,
logips2pp.c and in alps.c. All
> > mice have BTN_LEFT, but not all have BTN_MIDDLE (e.g.
Clevo D410J laptop). Mapping
> > BTN_FORWARD to mouse button 2 makes the BTN_FORWARD
button useful on the mentioned
> > laptop.
> >
> 
> I'd rather not touch mappings in legacy mousedev driver. I
believe
> both synaptics and evdev X drivers will correctly recognize
> BTN_FORWARD, is there any reason you are not using them?

If I have understand the input subsystem correctly, for the
evdev X driver the mousedev.c is not needed, so using an
evdev X driver is a completely other story. This map change
could result that the BTN_FORWARD can be used as BTN_MIDDLE
out of the box, without any additional drivers, so it is
simpler (at least in case of Clevo D410J).

My patch is based on the assumption that every mouse has
BTN_LEFT, so it is not worth having two mouse buttons for
the same function. (For Clevo D410J it is actually an
information loss at this point.)

Next thing is that the BTN_FORWARD and BTN_BACK usually
comes together. The BTN_LEFT and BTN_RIGHT usually comes
together also. For the mapping I see some possible mapping
listed in the following table:

    Button name    |     (a)     |     (b)     |     (c)     |
    ---------------+-------------+-------------+-------------+
    BTN_LEFT       |      0      |      0      |      0      |
    BTN_RIGHT      |      1      |      1      |      1      |
    BTN_FORWARD    |      0      |      2      |      0      |
    BTN_BACK       |      1      |      3      |      3      |

Mapping (a) would map BTN_FORWARD and BTN_BACK to BTN_LEFT
and BTN_RIGHT. Mapping (b) would map all 4 buttons to
different buttons. Mapping (c) is the current mapping where
the BTN_FORWARD is handled differently than BTN_BACK.

        NMarci

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