---

yaml
---
r: 178653
b: refs/heads/master
c: 94ec26c
h: refs/heads/master
i:
  178651: 87e486b
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1b11c88d3e8f55dc9d193d19de11e3f7abc1b7d7
+refs/heads/master: 94ec26c855bc675259e4f1658673f458040affd7

trunk/drivers/input/ff-memless.c

@@ -220,6 +220,22 @@ static int get_compatible_type(struct ff_device *ff, int effect_type)
 	return 0;
 }
 
+/*
+ * Only left/right direction should be used (under/over 0x8000) for
+ * forward/reverse motor direction (to keep calculation fast & simple).
+ */
+static u16 ml_calculate_direction(u16 direction, u16 force,
+				  u16 new_direction, u16 new_force)
+{
+	if (!force)
+		return new_direction;
+	if (!new_force)
+		return direction;
+	return (((u32)(direction >> 1) * force +
+		 (new_direction >> 1) * new_force) /
+		(force + new_force)) << 1;
+}
+
 /*
  * Combine two effects and apply gain.
  */
@@ -254,6 +270,19 @@ static void ml_combine_effects(struct ff_effect *effect,
 	case FF_RUMBLE:
 		strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
 		weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
+
+		if (effect->u.rumble.strong_magnitude + strong)
+			effect->direction = ml_calculate_direction(
+				effect->direction,
+				effect->u.rumble.strong_magnitude,
+				new->direction, strong);
+		else if (effect->u.rumble.weak_magnitude + weak)
+			effect->direction = ml_calculate_direction(
+				effect->direction,
+				effect->u.rumble.weak_magnitude,
+				new->direction, weak);
+		else
+			effect->direction = 0;
 		effect->u.rumble.strong_magnitude =
 			min(strong + effect->u.rumble.strong_magnitude,
 			    0xffffU);
@@ -268,6 +297,13 @@ static void ml_combine_effects(struct ff_effect *effect,
 		/* here we also scale it 0x7fff => 0xffff */
 		i = i * gain / 0x7fff;
 
+		if (effect->u.rumble.strong_magnitude + i)
+			effect->direction = ml_calculate_direction(
+				effect->direction,
+				effect->u.rumble.strong_magnitude,
+				new->direction, i);
+		else
+			effect->direction = 0;
 		effect->u.rumble.strong_magnitude =
 			min(i + effect->u.rumble.strong_magnitude, 0xffffU);
 		effect->u.rumble.weak_magnitude =