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Commit 00081d37 authored by Jason Parekh's avatar Jason Parekh Committed by Dmitry Torokhov
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Input: appletouch - verious updates for MacBooks 



Change a bit the finger detection method used by the appletouch
driver to reduce touchpad "jumpiness":

 - Adjust the method for detecting multiple fingers. Previously, it
   recognized a new finger when a low sensor reading is followed by
   a high sensor reading. The new method checks for 'humps' in the
   sensor readings, so there doesn't necessarily have to be a low
   sensor between two high sensors for two fingers to be triggered.
   This allows detecting presence of two fingers on the touchpad
   even when they touch each other.

 - Change absolute coordinate calculation to us to get rid of "jumps".
   Instead of using full value from a sensor once it passes the
   threshold subtract theshold value from the reading.

 - Allow adjusting threshold value via module parameter.

The patch doesn't seem to affect the Powerbooks but does greatly improve
the touchpad behaviour on the MacBooks.

Signed-off-by: default avatarJason Parekh <jasonparekh@gmail.com>
Signed-off-by: default avatarStelian Pop <stelian@popies.net>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent eb5d5829

drivers/usb/input/appletouch.c

+43 −4
Original line number Original line Diff line number Diff line
@@ -154,6 +154,13 @@ MODULE_AUTHOR("Johannes Berg, Stelian Pop, Frank Arnold, Michael Hanselmann"); 
MODULE_DESCRIPTION("Apple PowerBooks USB touchpad driver");

MODULE_DESCRIPTION("Apple PowerBooks USB touchpad driver");

MODULE_LICENSE("GPL");

MODULE_LICENSE("GPL");





/*

 * Make the threshold a module parameter

 */

static int threshold = ATP_THRESHOLD;

module_param(threshold, int, 0644);

MODULE_PARM_DESC(threshold, "Discards any change in data from a sensor (trackpad has hundreds of these sensors) less than this value");



static int debug = 1;

static int debug = 1;

module_param(debug, int, 0644);

module_param(debug, int, 0644);

MODULE_PARM_DESC(debug, "Activate debugging output");

MODULE_PARM_DESC(debug, "Activate debugging output");
@@ -183,16 +190,48 @@ static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact, 
	int i;

	int i;

	/* values to calculate mean */

	/* values to calculate mean */

	int pcum = 0, psum = 0;

	int pcum = 0, psum = 0;

	int is_increasing = 0;





	*fingers = 0;

	*fingers = 0;





	for (i = 0; i < nb_sensors; i++) {

	for (i = 0; i < nb_sensors; i++) {

		if (xy_sensors[i] < ATP_THRESHOLD)

		if (xy_sensors[i] < threshold) {

			if (is_increasing)

				is_increasing = 0;



			continue;

			continue;

		if ((i - 1 < 0) || (xy_sensors[i - 1] < ATP_THRESHOLD))

		}



		/*

		 * Makes the finger detection more versatile.  For example,

		 * two fingers with no gap will be detected.  Also, my

		 * tests show it less likely to have intermittent loss

		 * of multiple finger readings while moving around (scrolling).

		 *

		 * Changes the multiple finger detection to counting humps on

		 * sensors (transitions from nonincreasing to increasing)

		 * instead of counting transitions from low sensors (no

		 * finger reading) to high sensors (finger above

		 * sensor)

		 *

		 * - Jason Parekh <jasonparekh@gmail.com>

		 */

		if (i < 1 || (!is_increasing && xy_sensors[i - 1] < xy_sensors[i])) {

			(*fingers)++;

			(*fingers)++;

		pcum += xy_sensors[i] * i;

			is_increasing = 1;

		psum += xy_sensors[i];

		} else if (i > 0 && xy_sensors[i - 1] >= xy_sensors[i]) {

			is_increasing = 0;

		}



		/*

		 * Subtracts threshold so a high sensor that just passes the threshold

		 * won't skew the calculated absolute coordinate.  Fixes an issue

		 * where slowly moving the mouse would occassionaly jump a number of

		 * pixels (let me restate--slowly moving the mouse makes this issue

		 * most apparent).

		 */

		pcum += (xy_sensors[i] - threshold) * i;

		psum += (xy_sensors[i] - threshold);

	}

	}





	if (psum > 0) {

	if (psum > 0) {