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Input: appletouch - verious updates for MacBooks

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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: Jason Parekh <jasonparekh@gmail.com>
Signed-off-by: Stelian Pop <stelian@popies.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Jason Parekh 2006-11-17 01:05:58 -05:00 committed by Dmitry Torokhov
parent eb5d5829b3
commit 00081d3729
1 changed files with 43 additions and 4 deletions
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47
drivers/usb/input/appletouch.c
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@ -154,6 +154,13 @@ MODULE_AUTHOR("Johannes Berg, Stelian Pop, Frank Arnold, Michael Hanselmann");
MODULE_DESCRIPTION("Apple PowerBooks USB touchpad driver");
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;
module_param(debug, int, 0644);
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;
/* values to calculate mean */
int pcum = 0, psum = 0;
int is_increasing = 0;
*fingers = 0;
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;
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)++;
pcum += xy_sensors[i] * i;
psum += xy_sensors[i];
is_increasing = 1;
} 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) {