Input: atmel_mxt_ts - release touch state during suspend

If fingers are down as the MXT chip goes into suspend it does not send a lift
message. In addition, it may not complete its final measurement cycle
immediately, which means touch messages may be received by the interrupt
handler after mxt_stop() has completed.

So:
- disable irq during suspend
- flush any messages created after suspend
- tell app layer that slots were released at suspend

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
[cyrille.pitchen@atmel.com: adapt original patch to mainline]
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>

Author: ndyer

drivers/input/touchscreen/atmel_mxt_ts.c

@@ -325,6 +325,9 @@ struct mxt_data {
 
 	/* for config update handling */
 	struct completion crc_completion;
+
+	/* Indicates whether device is in suspend */
+	bool suspended;
 };
 
 struct mxt_vb2_buffer {
@@ -947,10 +950,10 @@ static int mxt_proc_message(struct mxt_data *data, u8 *message)
 
 	if (report_id == data->T6_reportid) {
 		mxt_proc_t6_messages(data, message);
-	} else if (!data->input_dev) {
+	} else if (!data->input_dev || data->suspended) {
 		/*
-		 * Do not report events if input device
-		 * is not yet registered.
+		 * Do not report events if input device is not
+		 * yet registered or returning from suspend.
 		 */
 		mxt_dump_message(data, message);
 	} else if (report_id >= data->T9_reportid_min &&
@@ -2761,6 +2764,11 @@ static int mxt_load_fw(struct device *dev, const char *fn)
 	if (ret)
 		goto release_firmware;
 
+	if (data->suspended) {
+		enable_irq(data->irq);
+		data->suspended = false;
+	}
+
 	if (!data->in_bootloader) {
 		/* Change to the bootloader mode */
 		data->in_bootloader = true;
@@ -2875,6 +2883,8 @@ static ssize_t mxt_update_fw_store(struct device *dev,
 	} else {
 		dev_info(dev, "The firmware update succeeded\n");
 
+		data->suspended = false;
+
 		error = mxt_initialize(data);
 		if (error)
 			return error;
@@ -2900,8 +2910,33 @@ static const struct attribute_group mxt_attr_group = {
 	.attrs = mxt_attrs,
 };
 
+static void mxt_reset_slots(struct mxt_data *data)
+{
+	struct input_dev *input_dev = data->input_dev;
+	int id;
+
+	if (!input_dev)
+		return;
+
+	for (id = 0; id < data->num_touchids; id++) {
+		input_mt_slot(input_dev, id);
+		input_mt_report_slot_state(input_dev, MT_TOOL_FINGER, 0);
+	}
+
+	mxt_input_sync(data);
+}
+
 static void mxt_start(struct mxt_data *data)
 {
+	if (!data->suspended || data->in_bootloader)
+		return;
+
+	/*
+	 * Discard any touch messages still in message buffer
+	 * from before chip went to sleep
+	 */
+	mxt_process_messages_until_invalid(data);
+
 	switch (data->pdata->suspend_mode) {
 	case MXT_SUSPEND_T9_CTRL:
 		mxt_soft_reset(data);
@@ -2921,10 +2956,17 @@ static void mxt_start(struct mxt_data *data)
 		break;
 	}
 
+	mxt_acquire_irq(data);
+	data->suspended = false;
 }
 
 static void mxt_stop(struct mxt_data *data)
 {
+	if (data->suspended || data->in_bootloader)
+		return;
+
+	disable_irq(data->irq);
+
 	switch (data->pdata->suspend_mode) {
 	case MXT_SUSPEND_T9_CTRL:
 		/* Touch disable */
@@ -2937,6 +2979,9 @@ static void mxt_stop(struct mxt_data *data)
 		mxt_set_t7_power_cfg(data, MXT_POWER_CFG_DEEPSLEEP);
 		break;
 	}
+
+	mxt_reset_slots(data);
+	data->suspended = true;
 }
 
 static int mxt_input_open(struct input_dev *dev)