input: edt-ft5x06: Handle unreliable TOUCH_UP events

The ft5x06 is unreliable in sending touch up events, so some
touch IDs can become stuck in the detected state.

Ensure that IDs that are unreported by the controller are
released.

Signed-off-by: Dave Stevenson <[email protected]>

Author: 6by9

drivers/input/touchscreen/edt-ft5x06.c

@@ -123,6 +123,7 @@ struct edt_ft5x06_ts_data {
 	int offset_y;
 	int report_rate;
 	int max_support_points;
+	unsigned int known_ids;
 
 	char name[EDT_NAME_LEN];
 
@@ -197,6 +198,9 @@ static irqreturn_t edt_ft5x06_ts_isr(int irq, void *dev_id)
 	int i, type, x, y, id;
 	int offset, tplen, datalen, crclen;
 	int error;
+	unsigned int active_ids = 0, known_ids = tsdata->known_ids;
+	long released_ids;
+	int b = 0;
 
 	switch (tsdata->version) {
 	case EDT_M06:
@@ -268,10 +272,25 @@ static irqreturn_t edt_ft5x06_ts_isr(int irq, void *dev_id)
 
 		input_mt_slot(tsdata->input, id);
 		if (input_mt_report_slot_state(tsdata->input, MT_TOOL_FINGER,
-					       type != TOUCH_EVENT_UP))
+					       type != TOUCH_EVENT_UP)) {
 			touchscreen_report_pos(tsdata->input, &tsdata->prop,
 					       x, y, true);
+			active_ids |= BIT(id);
+		} else {
+			known_ids &= ~BIT(id);
+		}
+	}
+
+	/* One issue with the device is the TOUCH_UP message is not always
+	 * returned. Instead track which ids we know about and report when they
+	 * are no longer updated
+	 */
+	released_ids = known_ids & ~active_ids;
+	for_each_set_bit_from(b, &released_ids, tsdata->max_support_points) {
+		input_mt_slot(tsdata->input, b);
+		input_mt_report_slot_inactive(tsdata->input);
 	}
+	tsdata->known_ids = active_ids;
 
 	input_mt_report_pointer_emulation(tsdata->input, true);
 	input_sync(tsdata->input);