Input: atmel_mxt_ts - delay enabling IRQ when not using regulators

The path of enabling the IRQ in the probe function is not safe in level
triggered operation, if it was already powered up and there is a message
waiting on the device (eg finger down) because the object table has not yet
been read. This forces the ISR into a hard loop.

Delay enabling the interrupt until it is first needed.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
[cyrille.pitchen@atmel.com: adapt original patch to mainline]
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
[eugen.hristev@microchip.com: adapt original patch to 4.14]
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

Author: ndyer

drivers/input/touchscreen/atmel_mxt_ts.c

@@ -1184,11 +1184,27 @@ static int mxt_acquire_irq(struct mxt_data *data)
 {
 	int error;
 
-	enable_irq(data->irq);
+	if (!data->irq) {
+		error = request_threaded_irq(data->client->irq, NULL,
+				mxt_interrupt,
+				data->pdata->irqflags | IRQF_ONESHOT,
+				data->client->name, data);
+		if (error) {
+			dev_err(&data->client->dev, "Error requesting irq\n");
+			return error;
+		}
 
-	error = mxt_process_messages_until_invalid(data);
-	if (error)
-		return error;
+		/* Presence of data->irq means IRQ initialised */
+		data->irq = data->client->irq;
+	} else {
+		enable_irq(data->irq);
+	}
+
+	if (data->object_table) {
+		error = mxt_process_messages_until_invalid(data);
+		if (error)
+			return error;
+	}
 
 	return 0;
 }
@@ -2878,7 +2894,7 @@ static int mxt_load_fw(struct device *dev, const char *fn)
 		mxt_free_input_device(data);
 		mxt_free_object_table(data);
 	} else {
-		enable_irq(data->irq);
+		mxt_acquire_irq(data);
 	}
 
 	reinit_completion(&data->chg_completion);
@@ -3322,7 +3338,6 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 	data->client = client;
 	data->pdata = pdata;
-	data->irq = client->irq;
 	i2c_set_clientdata(client, data);
 
 	init_completion(&data->chg_completion);
@@ -3359,15 +3374,17 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	}
 
 	if (pdata->suspend_mode == MXT_SUSPEND_REGULATOR) {
+		error = mxt_acquire_irq(data);
+		if (error)
+			return error;
+
 		error = mxt_probe_regulators(data);
 		if (error)
 			return error;
 
 		disable_irq(data->irq);
 	}
 
-	disable_irq(data->irq);
-
 	error = mxt_initialize(data);
 	if (error) {
 		/* Wait and try a second time */