diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index a3f492a..9c91b0b 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -5,6 +5,7 @@
  * Copyright (c) 2003-2005 Peter Osterlund <petero2@telia.com>
  * Copyright (c) 2004 Dmitry Torokhov <dtor@mail.ru>
  * Copyright (c) 2005 Vojtech Pavlik <vojtech@suse.cz>
+ * Copyright (c) 2009 Sebastian Kapfer <sebastian_kapfer@gmx.net>
  *
  * ALPS detection, tap switching and status querying info is taken from
  * tpconfig utility (by C. Scott Ananian and Bruce Kall).
@@ -28,7 +29,6 @@
 #define dbg(format, arg...) do {} while (0)
 #endif
 
-
 #define ALPS_OLDPROTO		0x01	/* old style input */
 #define ALPS_DUALPOINT		0x02	/* touchpad has trackstick */
 #define ALPS_PASS		0x04	/* device has a pass-through port */
@@ -37,7 +37,8 @@
 #define ALPS_FW_BK_1		0x10	/* front & back buttons present */
 #define ALPS_FW_BK_2		0x20	/* front & back buttons present */
 #define ALPS_FOUR_BUTTONS	0x40	/* 4 direction button present */
-
+#define ALPS_PS2_INTERLEAVED	0x80	/* 3-byte PS/2 packet interleaved with
+					   6-byte ALPS packet */
 
 static const struct alps_model_info alps_model_data[] = {
 	{ { 0x32, 0x02, 0x14 },	0xf8, 0xf8, ALPS_PASS | ALPS_DUALPOINT }, /* Toshiba Salellite Pro M10 */
@@ -58,7 +59,9 @@ static const struct alps_model_info alps_model_data[] = {
 	{ { 0x20, 0x02, 0x0e },	0xf8, 0xf8, ALPS_PASS | ALPS_DUALPOINT }, /* XXX */
 	{ { 0x22, 0x02, 0x0a },	0xf8, 0xf8, ALPS_PASS | ALPS_DUALPOINT },
 	{ { 0x22, 0x02, 0x14 }, 0xff, 0xff, ALPS_PASS | ALPS_DUALPOINT }, /* Dell Latitude D600 */
-	{ { 0x62, 0x02, 0x14 }, 0xcf, 0xcf, ALPS_PASS | ALPS_DUALPOINT }, /* Dell Latitude E6500 */
+	/* Dell Latitude E6400, E6500, Precision M4400 */
+	{ { 0x62, 0x02, 0x14 }, 0xcf, 0xcf,
+		ALPS_PASS | ALPS_DUALPOINT | ALPS_PS2_INTERLEAVED },
 	{ { 0x73, 0x02, 0x50 }, 0xcf, 0xcf, ALPS_FOUR_BUTTONS },	  /* Dell Vostro 1400 */
 };
 
@@ -69,7 +72,13 @@ static const struct alps_model_info alps_model_data[] = {
  */
 
 /*
- * ALPS abolute Mode - new format
+ * PS/2 packet format
+ *
+ * byte 0: YOFL XOFL YSGN XSGN  1    M    R    L
+ * byte 1: X7   X6   X5   X4   X3   X2   X1   X0
+ * byte 2: Y7   Y6   Y5   Y4   Y3   Y2   Y1   Y0
+ *
+ * ALPS absolute Mode - new format
  *
  * byte 0:  1    ?    ?    ?    1    ?    ?    ?
  * byte 1:  0   x6   x5   x4   x3   x2   x1   x0
@@ -78,6 +87,20 @@ static const struct alps_model_info alps_model_data[] = {
  * byte 4:  0   y6   y5   y4   y3   y2   y1   y0
  * byte 5:  0   z6   z5   z4   z3   z2   z1   z0
  *
+ * Dualpoint device -- interleaved packet format
+ *
+ * byte 0:    1    1    0    0    1    1    1    1
+ * byte 1:    0   x6   x5   x4   x3   x2   x1   x0
+ * byte 2:    0  x10   x9   x8   x7    0  fin  ges
+ * byte 3: YOFL XOFL YSGN XSGN    1    1    1    1
+ * byte 4:   X7   X6   X5   X4   X3   X2   X1   X0
+ * byte 5:   Y7   Y6   Y5   Y4   Y3   Y2   Y1   Y0
+ * byte 6:    0   y9   y8   y7    1    m    r    l
+ * byte 7:    0   y6   y5   y4   y3   y2   y1   y0
+ * byte 8:    0   z6   z5   z4   z3   z2   z1   z0
+ *
+ * CAPITALS = stick, miniscules = touchpad
+ *
  * ?'s can have different meanings on different models,
  * such as wheel rotation, extra buttons, stick buttons
  * on a dualpoint, etc.
@@ -93,18 +116,6 @@ static void alps_process_packet(struct psmouse *psmouse)
 	int x, y, z, ges, fin, left, right, middle;
 	int back = 0, forward = 0;
 
-	if ((packet[0] & 0xc8) == 0x08) {   /* 3-byte PS/2 packet */
-		input_report_key(dev2, BTN_LEFT,   packet[0] & 1);
-		input_report_key(dev2, BTN_RIGHT,  packet[0] & 2);
-		input_report_key(dev2, BTN_MIDDLE, packet[0] & 4);
-		input_report_rel(dev2, REL_X,
-			packet[1] ? packet[1] - ((packet[0] << 4) & 0x100) : 0);
-		input_report_rel(dev2, REL_Y,
-			packet[2] ? ((packet[0] << 3) & 0x100) - packet[2] : 0);
-		input_sync(dev2);
-		return;
-	}
-
 	if (model->flags & ALPS_OLDPROTO) {
 		left = packet[2] & 0x10;
 		right = packet[2] & 0x08;
@@ -202,25 +213,63 @@ static void alps_process_packet(struct psmouse *psmouse)
 	input_sync(dev);
 }
 
+static void alps_report_bare_ps2_packet(unsigned char packet[],
+					struct input_dev *dev)
+{
+	input_report_key(dev, BTN_LEFT,   packet[0] & 1);
+	input_report_key(dev, BTN_RIGHT,  packet[0] & 2);
+	input_report_key(dev, BTN_MIDDLE, packet[0] & 4);
+	input_report_rel(dev, REL_X,
+		packet[1] ? packet[1] - ((packet[0] << 4) & 0x100) : 0);
+	input_report_rel(dev, REL_Y,
+		packet[2] ? ((packet[0] << 3) & 0x100) - packet[2] : 0);
+	input_sync(dev);
+}
+
 static psmouse_ret_t alps_process_byte(struct psmouse *psmouse)
 {
 	struct alps_data *priv = psmouse->private;
+	const struct alps_model_info *model = priv->i;
 
 	if ((psmouse->packet[0] & 0xc8) == 0x08) { /* PS/2 packet */
 		if (psmouse->pktcnt == 3) {
-			alps_process_packet(psmouse);
+			alps_report_bare_ps2_packet(psmouse->packet,
+						    priv->dev2);
 			return PSMOUSE_FULL_PACKET;
 		}
 		return PSMOUSE_GOOD_DATA;
 	}
 
-	if ((psmouse->packet[0] & priv->i->mask0) != priv->i->byte0)
+	/* Check for PS/2 packet stuffed in the middle of ALPS packet. */
+
+	if ((model->flags & ALPS_PS2_INTERLEAVED) &&
+	    psmouse->pktcnt >= 4 && (psmouse->packet[3] & 0x0f) == 0x0f) {
+		if (psmouse->pktcnt < 7)
+			return PSMOUSE_GOOD_DATA;
+
+		/* Get the real button data */
+		psmouse->packet[3] &= psmouse->packet[6] & 0x0f;
+		alps_report_bare_ps2_packet(&psmouse->packet[3],
+					    priv->dev2);
+
+		/* Continue with the standard ALPS protocol handling */
+		psmouse->packet[3] = psmouse->packet[6];
+		psmouse->pktcnt = 4;
+	}
+
+	if ((psmouse->packet[0] & model->mask0) != model->byte0) {
+		dbg("refusing packet[0] = %x (mask0 = %x, byte0 = %x)\n",
+		    psmouse->packet[0], model->mask0, model->byte0);
 		return PSMOUSE_BAD_DATA;
+	}
 
 	/* Bytes 2 - 6 should have 0 in the highest bit */
 	if (psmouse->pktcnt >= 2 && psmouse->pktcnt <= 6 &&
-	    (psmouse->packet[psmouse->pktcnt - 1] & 0x80))
+	    (psmouse->packet[psmouse->pktcnt - 1] & 0x80)) {
+		dbg("refusing packet[%i] = %x\n",
+		    psmouse->pktcnt - 1, psmouse->packet[psmouse->pktcnt - 1]);
 		return PSMOUSE_BAD_DATA;
+	}
 
 	if (psmouse->pktcnt == 6) {
 		alps_process_packet(psmouse);
