[PATCH] input: fix BTN_TOUCH reporting in input_mt_report_pointer_emulation for hovering finger

[Chung-yih Wang <cywang@chromium.org>]

  From the definition of BTN_TOUCH, BTN_TOOL_<name> and BTN_TOUCH codes are
orthogonal. BTN_TOUCH should be zero if there is no physical contact, e.g.
hovering finger, happened on device. The patch uses touch_count and finger_count
to get the final reporting code for BTN_TOUCH and BTN_TOOL_<name>,
respectively. In addition, as there are some hard-coded pressure thresholds
defined in touch device's driver classes, 'touch_threshold' is introduced into
struct input_dev in order to tell if a finger is considered as a touch one in
input_mt_report_pointer_emulation().

---
 drivers/input/input-mt.c | 15 ++++++++++-----
 include/linux/input.h    |  2 ++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index fbe29fc..47e41d6 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -192,18 +192,21 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 {
 	struct input_mt *mt = dev->mt;
 	struct input_mt_slot *oldest;
-	int oldid, count, i;
+	int oldid, i;
+	int touch_count, finger_count;
 
 	if (!mt)
 		return;
 
 	oldest = NULL;
 	oldid = mt->trkid;
-	count = 0;
+	touch_count = 0;
+	finger_count = 0;
 
 	for (i = 0; i < mt->num_slots; ++i) {
 		struct input_mt_slot *ps = &mt->slots[i];
 		int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
+		int pressure = input_mt_get_value(ps, ABS_MT_PRESSURE);
 
 		if (id < 0)
 			continue;
@@ -211,12 +214,14 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 			oldest = ps;
 			oldid = id;
 		}
-		count++;
+		finger_count++;
+		if (pressure > dev->touch_threshold)
+			touch_count++;
 	}
 
-	input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
+	input_event(dev, EV_KEY, BTN_TOUCH, touch_count > 0);
 	if (use_count)
-		input_mt_report_finger_count(dev, count);
+		input_mt_report_finger_count(dev, finger_count);
 
 	if (oldest) {
 		int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
diff --git a/include/linux/input.h b/include/linux/input.h
index 82ce323..5b2739d 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -187,6 +187,8 @@ struct input_dev {
 	struct input_value *vals;
 
 	bool devres_managed;
+
+	unsigned int touch_threshold;
 };
 #define to_input_dev(d) container_of(d, struct input_dev, dev)
 
-- 
2.0.0.526.g5318336