Re: [PATCH] Synaptics TouchPad driver for 2.5.70

[Peter Osterlund]

Vojtech Pavlik <[e-mail]> writes:

> On Wed, Jun 11, 2003 at 07:05:31AM +0200, Peter Osterlund wrote:
> > 
> > Here is a driver for the Synaptics TouchPad for 2.5.70.
...
> > The only major missing feature is runtime configuration of driver
> > parameters. What is the best way to implement that?
> 
> sysfs, of course.

Actually, the runtime configuration may not be needed at all if we do
the ABS -> REL conversion in user space, because all parameters
control different aspects of this conversion.

> > The patch is available here:
> > 
> >         http://w1.894.telia.com/~u89404340/patches/synaptics_driver.patch
> > 
> > Comments?
> 
> IMO it should use ABS_ events and the relativization should be done in
> the XFree86 driver. Other than that, it looks quite OK.

OK, the hardware state consists of 4 "axes" and 4 buttons, as defined
in the synaptics_hw_state struct:

        struct synaptics_hw_state {
        	int x;
        	int y;
        	int z;
        	int w;
        	int left;
        	int right;
        	int up;
        	int down;
        };

x and y are the finger position, z is the finger pressure and w
contains information about multifinger taps and finger width (for palm
detection.) Left, right, up and down contain the state of the
corresponding physical buttons.

Is this mapping reasonable?

        x     -> ABS_X
        y     -> ABS_Y
        z     -> ABS_PRESSURE
        w     -> ABS_MISC
        left  -> BTN_LEFT
        right -> BTN_RIGHT
        up    -> BTN_FORWARD
        down  -> BTN_BACK

The w value is somewhat special and not really a real axis. According
to the Synaptics TouchPad Interfacing Guide
(http://www.synaptics.com/decaf/utilities/ACF126.pdf), W is defined as
follows:

Value		Needed capability	Interpretation
W = 0		capMultiFinger		Two fingers on the pad.
W = 1		capMultiFinger		Three or more fingers on the pad.
W = 2		capPen			Pen (instead of finger) on the pad.
W = 3		Reserved.
W = 4-7		capPalmDetect		Finger of normal width.
W = 8-14	capPalmDetect		Very wide finger or palm.
W = 15		capPalmDetect		Maximum reportable width; extremely
					wide contact.

Is there a better way than using ABS_MISC to pass the W information to
user space?

-- 
Peter Osterlund - [e-mail]
http://w1.894.telia.com/~u89404340