Input: ar1021_i2c - enable touch mode during open

The device could as well be in command mode, in which this driver cannot
handle the device. When opening the device, let's make sure the device
will be in the mode we expect it to be for this driver.
Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/ar1021_i2c.c

@@ -18,6 +18,10 @@
 #define AR1021_MAX_X	4095
 #define AR1021_MAX_Y	4095
 
+#define AR1021_CMD	0x55
+
+#define AR1021_CMD_ENABLE_TOUCH		0x12
+
 struct ar1021_i2c {
 	struct i2c_client *client;
 	struct input_dev *input;
@@ -56,8 +60,19 @@ static irqreturn_t ar1021_i2c_irq(int irq, void *dev_id)
 
 static int ar1021_i2c_open(struct input_dev *dev)
 {
+	static const u8 cmd_enable_touch[] = {
+		AR1021_CMD,
+		0x01, /* number of bytes after this */
+		AR1021_CMD_ENABLE_TOUCH
+	};
 	struct ar1021_i2c *ar1021 = input_get_drvdata(dev);
 	struct i2c_client *client = ar1021->client;
+	int error;
+
+	error = i2c_master_send(ar1021->client, cmd_enable_touch,
+				sizeof(cmd_enable_touch));
+	if (error < 0)
+		return error;
 
 	enable_irq(client->irq);