1 files changed, 46 insertions, 10 deletions

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index d125a019383f..54ff03791940 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -919,18 +919,21 @@ static void alps_get_finger_coordinate_v7(struct input_mt_pos *mt,
 
 static int alps_get_mt_count(struct input_mt_pos *mt)
 {
-	int i;
+	int i, fingers = 0;
 
-	for (i = 0; i < MAX_TOUCHES && mt[i].x != 0 && mt[i].y != 0; i++)
-		/* empty */;
+	for (i = 0; i < MAX_TOUCHES; i++) {
+		if (mt[i].x != 0 || mt[i].y != 0)
+			fingers++;
+	}
 
-	return i;
+	return fingers;
 }
 
 static int alps_decode_packet_v7(struct alps_fields *f,
 				  unsigned char *p,
 				  struct psmouse *psmouse)
 {
+	struct alps_data *priv = psmouse->private;
 	unsigned char pkt_id;
 
 	pkt_id = alps_get_packet_id_v7(p);
@@ -938,19 +941,52 @@ static int alps_decode_packet_v7(struct alps_fields *f,
 		return 0;
 	if (pkt_id == V7_PACKET_ID_UNKNOWN)
 		return -1;
+	/*
+	 * NEW packets are send to indicate a discontinuity in the finger
+	 * coordinate reporting. Specifically a finger may have moved from
+	 * slot 0 to 1 or vice versa. INPUT_MT_TRACK takes care of this for
+	 * us.
+	 *
+	 * NEW packets have 3 problems:
+	 * 1) They do not contain middle / right button info (on non clickpads)
+	 *    this can be worked around by preserving the old button state
+	 * 2) They do not contain an accurate fingercount, and they are
+	 *    typically send when the number of fingers changes. We cannot use
+	 *    the old finger count as that may mismatch with the amount of
+	 *    touch coordinates we've available in the NEW packet
+	 * 3) Their x data for the second touch is inaccurate leading to
+	 *    a possible jump of the x coordinate by 16 units when the first
+	 *    non NEW packet comes in
+	 * Since problems 2 & 3 cannot be worked around, just ignore them.
+	 */
+	if (pkt_id == V7_PACKET_ID_NEW)
+		return 1;
 
 	alps_get_finger_coordinate_v7(f->mt, p, pkt_id);
 
-	if (pkt_id == V7_PACKET_ID_TWO || pkt_id == V7_PACKET_ID_MULTI) {
-		f->left = (p[0] & 0x80) >> 7;
+	if (pkt_id == V7_PACKET_ID_TWO)
+		f->fingers = alps_get_mt_count(f->mt);
+	else /* pkt_id == V7_PACKET_ID_MULTI */
+		f->fingers = 3 + (p[5] & 0x03);
+
+	f->left = (p[0] & 0x80) >> 7;
+	if (priv->flags & ALPS_BUTTONPAD) {
+		if (p[0] & 0x20)
+			f->fingers++;
+		if (p[0] & 0x10)
+			f->fingers++;
+	} else {
 		f->right = (p[0] & 0x20) >> 5;
 		f->middle = (p[0] & 0x10) >> 4;
 	}
 
-	if (pkt_id == V7_PACKET_ID_TWO)
-		f->fingers = alps_get_mt_count(f->mt);
-	else if (pkt_id == V7_PACKET_ID_MULTI)
-		f->fingers = 3 + (p[5] & 0x03);
+	/* Sometimes a single touch is reported in mt[1] rather then mt[0] */
+	if (f->fingers == 1 && f->mt[0].x == 0 && f->mt[0].y == 0) {
+		f->mt[0].x = f->mt[1].x;
+		f->mt[0].y = f->mt[1].y;
+		f->mt[1].x = 0;
+		f->mt[1].y = 0;
+	}
 
 	return 0;
 }