input: Here it is, with the suggestions from Pete and Dmitry included. The

patch does the following:

* Compensates for the lack of floating point arithmetic by keeping
  track of remainders from the integer divisions.
* Removes the xres/yres scaling so that you get the same speed in the
  X and Y directions even if your screen does not the same aspect ratio
  as your touchpad.
* Sets scale factors to make the speed for synaptics and alps equal to
  each other and equal to the synaptics speed from 2.6.10.
Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>

drivers/input/mousedev.c

@@ -71,6 +71,7 @@ struct mousedev {
 	struct mousedev_hw_data packet;
 	unsigned int pkt_count;
 	int old_x[4], old_y[4];
+	int frac_dx, frac_dy;
 	unsigned long touch;
 };
 
@@ -117,24 +118,31 @@ static struct mousedev mousedev_mix;
 
 static void mousedev_touchpad_event(struct input_dev *dev, struct mousedev *mousedev, unsigned int code, int value)
 {
-	int size;
+	int size, tmp;
+	enum { FRACTION_DENOM = 128 };
 
 	if (mousedev->touch) {
+		size = dev->absmax[ABS_X] - dev->absmin[ABS_X];
+		if (size == 0) size = 256 * 2;
 		switch (code) {
 			case ABS_X:
-				size = dev->absmax[ABS_X] - dev->absmin[ABS_X];
-				if (size == 0) size = xres;
 				fx(0) = value;
-				if (mousedev->pkt_count >= 2)
-					mousedev->packet.dx = ((fx(0) - fx(1)) / 2 + (fx(1) - fx(2)) / 2) * xres / (size * 2);
+				if (mousedev->pkt_count >= 2) {
+					tmp = ((value - fx(2)) * (256 * FRACTION_DENOM)) / size;
+					tmp += mousedev->frac_dx;
+					mousedev->packet.dx = tmp / FRACTION_DENOM;
+					mousedev->frac_dx = tmp - mousedev->packet.dx * FRACTION_DENOM;
+				}
 				break;
 
 			case ABS_Y:
-				size = dev->absmax[ABS_Y] - dev->absmin[ABS_Y];
-				if (size == 0) size = yres;
 				fy(0) = value;
-				if (mousedev->pkt_count >= 2)
-					mousedev->packet.dy = -((fy(0) - fy(1)) / 2 + (fy(1) - fy(2)) / 2) * yres / (size * 2);
+				if (mousedev->pkt_count >= 2) {
+					tmp = -((value - fy(2)) * (256 * FRACTION_DENOM)) / size;
+					tmp += mousedev->frac_dy;
+					mousedev->packet.dy = tmp / FRACTION_DENOM;
+					mousedev->frac_dy = tmp - mousedev->packet.dy * FRACTION_DENOM;
+				}
 				break;
 		}
 	}
@@ -268,6 +276,8 @@ static void mousedev_touchpad_touch(struct mousedev *mousedev, int value)
 			clear_bit(0, &mousedev_mix.packet.buttons);
 		}
 		mousedev->touch = mousedev->pkt_count = 0;
+		mousedev->frac_dx = 0;
+		mousedev->frac_dy = 0;
 	}
 	else
 		if (!mousedev->touch)