@@ -659,6 +659,7 @@ static void synaptics_image_sensor_0f(struct synaptics_data *priv,
 				      struct synaptics_mt_state *mt_state)
 {
 	synaptics_mt_state_set(mt_state, 0, -1, -1);
+	priv->mt_state_lost = false;
 }
 
 /* Handle case where mt_state->count = 1 */

@@ -726,6 +727,7 @@ static void synaptics_image_sensor_1f(struct synaptics_data *priv,
 		 * So, empty all slots. We will guess slot 0 on subsequent 1->1
 		 */
 		synaptics_mt_state_set(mt_state, 0, -1, -1);
+		priv->mt_state_lost = true;
 		break;
 	}
 }

@@ -771,6 +773,7 @@ static void synaptics_image_sensor_2f(struct synaptics_data *priv,
 		 * subsequent 2->2
 		 */
 		synaptics_mt_state_set(mt_state, 0, -1, -1);
+		priv->mt_state_lost = true;
 		break;
 	}
 }

@@ -800,14 +803,32 @@ static void synaptics_image_sensor_3f(struct synaptics_data *priv,
 		break;
 	case 2:
 		/*
-		 * On 2->3 transitions, we are given no indication which finger
-		 * was added.
-		 * We don't even know what finger the current AGM packet
-		 * contained.
+		 * After some 3->1 and all 3->2 transitions, we lose track
+		 * of which slot is reported by sgm and agm.
 		 *
-		 * So, empty all slots. They get filled on a subsequent 3->3
+		 * For 2->3 in this state, empty all slots, and we will guess
+		 * (0,1) on a subsequent 0->3.
+		 *
+		 * To userspace, the resulting transition will look like:
+		 *    2:[0,1] -> 0:[-1,-1] -> 3:[0,2]
 		 */
-		synaptics_mt_state_set(mt_state, 0, -1, -1);
+		if (priv->mt_state_lost) {
+			synaptics_mt_state_set(mt_state, 0, -1, -1);
+			break;
+		}
+
+		/*
+		 * If the (SGM,AGM) really previously contained slots (0, 1),
+		 * then we cannot know what slot was just reported by the AGM,
+		 * because the 2->3 transition can occur either before or after
+		 * the AGM packet. Thus, this most recent AGM could contain
+		 * either the same old slot 1 or the new slot 2.
+		 * Subsequent AGMs will be reporting slot 2.
+		 *
+		 * To userspace, the resulting transition will look like:
+		 *    2:[0,1] -> 1:[0,-1] -> 3:[0,2]
+		 */
+		synaptics_mt_state_set(mt_state, 1, 0, -1);
 		break;
 	case 3:
 		/*

@@ -162,6 +162,7 @@ struct synaptics_data {
 	struct serio *pt_port;			/* Pass-through serio port */
 
 	struct synaptics_mt_state mt_state;	/* Current mt finger state */
+	bool mt_state_lost;			/* mt_state may be incorrect */
 
 	/*
 	 * Last received Advanced Gesture Mode (AGM) packet. An AGM packet