1 files changed, 51 insertions, 1 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 3464adab0085..40fbb7c52723 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -118,6 +118,9 @@ struct mt_application {
 	int left_button_state;		/* left button state */
 	unsigned int mt_flags;		/* flags to pass to input-mt */
 
+	unsigned long *pending_palm_slots;	/* slots where we reported palm
+						 * and need to release */
+
 	__u8 num_received;	/* how many contacts we received */
 	__u8 num_expected;	/* expected last contact index */
 	__u8 buttons_count;	/* number of physical buttons per touchpad */
@@ -863,6 +866,28 @@ static int mt_compute_slot(struct mt_device *td, struct mt_application *app,
 	return input_mt_get_slot_by_key(input, *slot->contactid);
 }
 
+static void mt_release_pending_palms(struct mt_device *td,
+				     struct mt_application *app,
+				     struct input_dev *input)
+{
+	int slotnum;
+	bool need_sync = false;
+
+	for_each_set_bit(slotnum, app->pending_palm_slots, td->maxcontacts) {
+		clear_bit(slotnum, app->pending_palm_slots);
+
+		input_mt_slot(input, slotnum);
+		input_mt_report_slot_state(input, MT_TOOL_PALM, false);
+
+		need_sync = true;
+	}
+
+	if (need_sync) {
+		input_mt_sync_frame(input);
+		input_sync(input);
+	}
+}
+
 /*
  * this function is called when a whole packet has been received and processed,
  * so that it can decide what to send to the input layer.
@@ -876,6 +901,9 @@ static void mt_sync_frame(struct mt_device *td, struct mt_application *app,
 	input_mt_sync_frame(input);
 	input_event(input, EV_MSC, MSC_TIMESTAMP, app->timestamp);
 	input_sync(input);
+
+	mt_release_pending_palms(td, app, input);
+
 	app->num_received = 0;
 	app->left_button_state = 0;
 
@@ -970,8 +998,23 @@ static int mt_process_slot(struct mt_device *td, struct input_dev *input,
 
 	if (app->application == HID_GD_SYSTEM_MULTIAXIS)
 		tool = MT_TOOL_DIAL;
-	else if (unlikely(!confidence_state))
+	else if (unlikely(!confidence_state)) {
 		tool = MT_TOOL_PALM;
+		if (!active &&
+		    input_mt_is_active(&mt->slots[slotnum])) {
+			/*
+			 * The non-confidence was reported for
+			 * previously valid contact that is also no
+			 * longer valid. We can't simply report
+			 * lift-off as userspace will not be aware
+			 * of non-confidence, so we need to split
+			 * it into 2 events: active MT_TOOL_PALM
+			 * and a separate liftoff.
+			 */
+			active = true;
+			set_bit(slotnum, app->pending_palm_slots);
+		}
+	}
 
 	input_mt_slot(input, slotnum);
 	input_mt_report_slot_state(input, tool, active);
@@ -1197,6 +1240,13 @@ static int mt_touch_input_configured(struct hid_device *hdev,
 	if (td->is_buttonpad)
 		__set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
 
+	app->pending_palm_slots = devm_kcalloc(&hi->input->dev,
+					       BITS_TO_LONGS(td->maxcontacts),
+					       sizeof(long),
+					       GFP_KERNEL);
+	if (!app->pending_palm_slots)
+		return -ENOMEM;
+
 	ret = input_mt_init_slots(input, td->maxcontacts, app->mt_flags);
 	if (ret)
 		return ret;