Commit 448c7f38 authored by Henrik Rydberg's avatar Henrik Rydberg Committed by Dmitry Torokhov
Browse files

Input: MT - add support for balanced slot assignment 



Some devices are not fast enough to differentiate between a fast-moving
contact and a new contact. This problem cannot be fully resolved because
information is truly missing, but it is possible to safe-guard against
obvious mistakes by restricting movement with a maximum displacement.

The new problem formulation for dmax > 0 cannot benefit from the speedup
for positive definite matrices, but since the convergence is faster, the
result is about the same. For a handful of contacts, the latency difference
is truly negligible.

Suggested-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: default avatarHenrik Rydberg <rydberg@bitmath.org>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 60bcaae1

drivers/input/input-mt.c

+20 −11
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ void input_mt_sync_frame(struct input_dev *dev) 
}

EXPORT_SYMBOL(input_mt_sync_frame);



static int adjust_dual(int *begin, int step, int *end, int eq)

static int adjust_dual(int *begin, int step, int *end, int eq, int mu)

{

	int f, *p, s, c;
@@ -311,9 +311,10 @@ static int adjust_dual(int *begin, int step, int *end, int eq) 
			s = *p;



	c = (f + s + 1) / 2;

	if (c == 0 || (c > 0 && !eq))

	if (c == 0 || (c > mu && (!eq || mu > 0)))

		return 0;

	if (s < 0)

	/* Improve convergence for positive matrices by penalizing overcovers */

	if (s < 0 && mu <= 0)

		c *= 2;



	for (p = begin; p != end; p += step)
@@ -322,23 +323,24 @@ static int adjust_dual(int *begin, int step, int *end, int eq) 
	return (c < s && s <= 0) || (f >= 0 && f < c);

}



static void find_reduced_matrix(int *w, int nr, int nc, int nrc)

static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)

{

	int i, k, sum;



	for (k = 0; k < nrc; k++) {

		for (i = 0; i < nr; i++)

			adjust_dual(w + i, nr, w + i + nrc, nr <= nc);

			adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);

		sum = 0;

		for (i = 0; i < nrc; i += nr)

			sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr);

			sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);

		if (!sum)

			break;

	}

}



static int input_mt_set_matrix(struct input_mt *mt,

			       const struct input_mt_pos *pos, int num_pos)

			       const struct input_mt_pos *pos, int num_pos,

			       int mu)

{

	const struct input_mt_pos *p;

	struct input_mt_slot *s;
@@ -352,7 +354,7 @@ static int input_mt_set_matrix(struct input_mt *mt, 
		y = input_mt_get_value(s, ABS_MT_POSITION_Y);

		for (p = pos; p != pos + num_pos; p++) {

			int dx = x - p->x, dy = y - p->y;

			*w++ = dx * dx + dy * dy;

			*w++ = dx * dx + dy * dy - mu;

		}

	}
@@ -393,17 +395,24 @@ static void input_mt_set_slots(struct input_mt *mt, 
 * @slots: the slot assignment to be filled

 * @pos: the position array to match

 * @num_pos: number of positions

 * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)

 *

 * Performs a best match against the current contacts and returns

 * the slot assignment list. New contacts are assigned to unused

 * slots.

 *

 * The assignments are balanced so that all coordinate displacements are

 * below the euclidian distance dmax. If no such assignment can be found,

 * some contacts are assigned to unused slots.

 *

 * Returns zero on success, or negative error in case of failure.

 */

int input_mt_assign_slots(struct input_dev *dev, int *slots,

			  const struct input_mt_pos *pos, int num_pos)

			  const struct input_mt_pos *pos, int num_pos,

			  int dmax)

{

	struct input_mt *mt = dev->mt;

	int mu = 2 * dmax * dmax;

	int nrc;



	if (!mt || !mt->red)
@@ -413,8 +422,8 @@ int input_mt_assign_slots(struct input_dev *dev, int *slots, 
	if (num_pos < 1)

		return 0;



	nrc = input_mt_set_matrix(mt, pos, num_pos);

	find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc);

	nrc = input_mt_set_matrix(mt, pos, num_pos, mu);

	find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);

	input_mt_set_slots(mt, slots, num_pos);



	return 0;

drivers/input/mouse/alps.c

+1 −1
Original line number Diff line number Diff line
@@ -435,7 +435,7 @@ static void alps_report_mt_data(struct psmouse *psmouse, int n) 
	struct alps_fields *f = &priv->f;

	int i, slot[MAX_TOUCHES];



	input_mt_assign_slots(dev, slot, f->mt, n);

	input_mt_assign_slots(dev, slot, f->mt, n, 0);

	for (i = 0; i < n; i++)

		alps_set_slot(dev, slot[i], f->mt[i].x, f->mt[i].y);

drivers/input/mouse/bcm5974.c

+1 −1
Original line number Diff line number Diff line
@@ -564,7 +564,7 @@ static int report_tp_state(struct bcm5974 *dev, int size) 
		dev->index[n++] = &f[i];

	}



	input_mt_assign_slots(input, dev->slots, dev->pos, n);

	input_mt_assign_slots(input, dev->slots, dev->pos, n, 0);



	for (i = 0; i < n; i++)

		report_finger_data(input, dev->slots[i],

drivers/input/mouse/cypress_ps2.c

+1 −1
Original line number Diff line number Diff line
@@ -538,7 +538,7 @@ static void cypress_process_packet(struct psmouse *psmouse, bool zero_pkt) 
		pos[i].y = contact->y;

	}



	input_mt_assign_slots(input, slots, pos, n);

	input_mt_assign_slots(input, slots, pos, n, 0);



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

		contact = &report_data.contacts[i];

drivers/input/mouse/synaptics.c

+1 −1
Original line number Diff line number Diff line
@@ -809,7 +809,7 @@ static void synaptics_report_mt_data(struct psmouse *psmouse, 
		pos[i].y = synaptics_invert_y(hw[i]->y);

	}



	input_mt_assign_slots(dev, slot, pos, nsemi);

	input_mt_assign_slots(dev, slot, pos, nsemi, 0);



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

		input_mt_slot(dev, slot[i]);

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