HID: magicmouse: simplify touch down logic

For the MT protocol, we need to properly keep track of each down touch.
This change simplifies the logic, and should make things easier when
support for the Magic Trackpad is added.
Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Michael Poole <mdpoole@troilus.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-magicmouse.c

@@ -98,7 +98,6 @@ struct magicmouse_sc {
 		short scroll_x;
 		short scroll_y;
 		u8 size;
-		u8 down;
 	} touches[16];
 	int tracking_ids[16];
 };
@@ -226,8 +225,6 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
 	if (report_touches && down) {
 		int orientation = (misc >> 10) - 32;
 
-		msc->touches[id].down = 1;
-
 		input_report_abs(input, ABS_MT_TRACKING_ID, id);
 		input_report_abs(input, ABS_MT_TOUCH_MAJOR, tdata[3]);
 		input_report_abs(input, ABS_MT_TOUCH_MINOR, tdata[4]);
@@ -240,6 +237,9 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
 
 		input_mt_sync(input);
 	}
+
+	if (down)
+		msc->ntouches++;
 }
 
 static int magicmouse_raw_event(struct hid_device *hdev,
@@ -247,7 +247,7 @@ static int magicmouse_raw_event(struct hid_device *hdev,
 {
 	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
 	struct input_dev *input = msc->input;
-	int x, y, ts, ii, clicks, last_up;
+	int x, y, ts, ii, clicks, npoints;
 
 	switch (data[0]) {
 	case 0x10:
@@ -264,22 +264,13 @@ static int magicmouse_raw_event(struct hid_device *hdev,
 		ts = data[3] >> 6 | data[4] << 2 | data[5] << 10;
 		msc->delta_time = (ts - msc->last_timestamp) & 0x3ffff;
 		msc->last_timestamp = ts;
-		msc->ntouches = (size - 6) / 8;
-		for (ii = 0; ii < msc->ntouches; ii++)
+		npoints = (size - 6) / 8;
+		msc->ntouches = 0;
+		for (ii = 0; ii < npoints; ii++)
 			magicmouse_emit_touch(msc, ii, data + ii * 8 + 6);
 
-		if (report_touches) {
-			last_up = 1;
-			for (ii = 0; ii < ARRAY_SIZE(msc->touches); ii++) {
-				if (msc->touches[ii].down) {
-					last_up = 0;
-					msc->touches[ii].down = 0;
-				}
-			}
-			if (last_up) {
-				input_mt_sync(input);
-			}
-		}
+		if (report_touches && msc->ntouches == 0)
+			input_mt_sync(input);
 
 		/* When emulating three-button mode, it is important
 		 * to have the current touch information before