[PATCH 01/01] Input multitouch: fix horizontal two-finger-scrollingon Sentelic touchpads

[Christophe TORDEUX]

From: Christophe TORDEUX <christophe@xxxxxxxxxxx>

Fix horizontal two-finger scrolling on Sentelic touchpads. Currently
horizontal two-fingers scrolling does not work with these touchpads.
The patch also makes vertical two-finger scrolling smoother in some
applications e.g. Firefox.

Signed-off-by: Christophe TORDEUX <christophe@xxxxxxxxxxx>
----

This patch was inspired by the reading of
drivers/input/mouse/synaptics.c. It is known to work (tested) on
Sentelic touchpads version STL3888_C0. Very probably works on all later
versions, and possibly works on some earlier versions of the hardware in
question.

diff -uprN -X vanilla/linux-3.7-rc8/Documentation/dontdiff 
vanilla/linux-3.7-rc8/drivers/input/mouse/sentelic.c 
linux-3.7-rc8/drivers/input/mouse/sentelic.c
--- vanilla/linux-3.7-rc8/drivers/input/mouse/sentelic.c	2012-12-11 04:32:44.476930522 +0100
+++ linux-3.7-rc8/drivers/input/mouse/sentelic.c	2012-12-12 01:16:41.766018017 +0100
@@ -706,8 +706,10 @@ static psmouse_ret_t fsp_process_byte(st
 	struct input_dev *dev = psmouse->dev;
 	struct fsp_data *ad = psmouse->private;
 	unsigned char *packet = psmouse->packet;
+	unsigned char *last_packet = ad->last_pkt;
 	unsigned char button_status = 0, lscroll = 0, rscroll = 0;
 	unsigned short abs_x, abs_y, fgrs = 0;
+	unsigned short last_abs_x, last_abs_y;
 	int rel_x, rel_y;
 
 	if (psmouse->pktcnt < 4)
@@ -734,6 +736,9 @@ static psmouse_ret_t fsp_process_byte(st
 
 		abs_x = GET_ABS_X(packet);
 		abs_y = GET_ABS_Y(packet);
+		last_abs_x = GET_ABS_X(last_packet);
+		last_abs_y = GET_ABS_Y(last_packet);
+		memcpy(ad->last_pkt, packet, psmouse->pktcnt);
 
 		if (packet[0] & FSP_PB0_MFMC) {
 			/*
@@ -753,10 +758,19 @@ static psmouse_ret_t fsp_process_byte(st
 					 */
 					fgrs = 1;
 					fsp_set_slot(dev, 0, false, 0, 0);
+
+					/* We don't need to re-order
+					 * coordinates if last finger
+					 * was same finger
+					 */
+					last_abs_x = abs_x;
+					last_abs_y = abs_y;
 				}
 				ad->last_mt_fgr = 2;
 
-				fsp_set_slot(dev, 1, fgrs == 2, abs_x, abs_y);
+				fsp_set_slot(dev, 1, fgrs == 2,
+						max(abs_x, last_abs_x),
+						max(abs_y, last_abs_y));
 			} else {
 				/* 1st finger */
 				if (ad->last_mt_fgr == 1) {
@@ -767,9 +781,18 @@ static psmouse_ret_t fsp_process_byte(st
 					 */
 					fgrs = 1;
 					fsp_set_slot(dev, 1, false, 0, 0);
+
+					/* We don't need to re-order
+					 * coordinates if last finger
+					 * was same finger
+					 */
+					last_abs_x = abs_x;
+					last_abs_y = abs_y;
 				}
 				ad->last_mt_fgr = 1;
-				fsp_set_slot(dev, 0, fgrs != 0, abs_x, abs_y);
+				fsp_set_slot(dev, 0, fgrs != 0,
+						min(abs_x, last_abs_x),
+						min(abs_y, last_abs_y));
 			}
 		} else {
 			/* SFAC packet */
@@ -788,12 +811,18 @@ static psmouse_ret_t fsp_process_byte(st
 			if (abs_x != 0 && abs_y != 0)
 				fgrs = 1;
 
+			/* We don't need to re-order
+			 * coordinates of SFAC packets
+			 */
+			last_abs_x = abs_x;
+			last_abs_y = abs_y;
+
 			fsp_set_slot(dev, 0, fgrs > 0, abs_x, abs_y);
 			fsp_set_slot(dev, 1, false, 0, 0);
 		}
 		if (fgrs > 0) {
-			input_report_abs(dev, ABS_X, abs_x);
-			input_report_abs(dev, ABS_Y, abs_y);
+			input_report_abs(dev, ABS_X, min(abs_x, last_abs_x));
+			input_report_abs(dev, ABS_Y, min(abs_y, last_abs_y));
 		}
 		input_report_key(dev, BTN_LEFT, packet[0] & 0x01);
 		input_report_key(dev, BTN_RIGHT, packet[0] & 0x02);
diff -uprN -X vanilla/linux-3.7-rc8/Documentation/dontdiff vanilla/linux-3.7-rc8/drivers/input/mouse/sentelic.h linux-3.7-rc8/drivers/input/mouse/sentelic.h
--- vanilla/linux-3.7-rc8/drivers/input/mouse/sentelic.h	2012-12-11 04:32:44.476930522 +0100
+++ linux-3.7-rc8/drivers/input/mouse/sentelic.h	2012-12-12 01:16:41.954018011 +0100
@@ -117,6 +117,7 @@ struct fsp_data {
 	unsigned char	last_reg;	/* Last register we requested read from */
 	unsigned char	last_val;
 	unsigned int	last_mt_fgr;	/* Last seen finger(multitouch) */
+	unsigned char	last_pkt[8];    /* Last packet we processed from fsp */
 };
 
 #ifdef CONFIG_MOUSE_PS2_SENTELIC

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