Input: elan_i2c - make fetching IC type of older controllers more robust

On older controllers IC type is reported in the 2nd byte of
ETP_I2C_OSM_VERSION_CMD, however if controller's firmware is not flashed
correctly it may return incorrect data. Fortunately there is also
ETP_I2C_IAP_VERSION_P0_CMD command that can be used when controller in
either normal or IAP mode, and which is guaranteed to return accurate data,
so let's use it.
Signed-off-by: Jingle Wu <jingle.wu@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elan_i2c_core.c

@@ -312,7 +312,6 @@ static int elan_initialize(struct elan_tp_data *data)
 static int elan_query_device_info(struct elan_tp_data *data)
 {
 	int error;
-	u16 ic_type;
 
 	error = data->ops->get_version(data->client, false, &data->fw_version);
 	if (error)
@@ -336,12 +335,7 @@ static int elan_query_device_info(struct elan_tp_data *data)
 	if (error)
 		return error;
 
-	if (data->pattern == 0x01)
-		ic_type = data->ic_type;
-	else
-		ic_type = data->iap_version;
-
-	error = elan_get_fwinfo(ic_type, &data->fw_validpage_count,
+	error = elan_get_fwinfo(data->ic_type, &data->fw_validpage_count,
 				&data->fw_signature_address);
 	if (error)
 		dev_warn(&data->client->dev,

drivers/input/mouse/elan_i2c_i2c.c

@@ -43,6 +43,7 @@
 #define ETP_I2C_RESOLUTION_CMD		0x0108
 #define ETP_I2C_PRESSURE_CMD		0x010A
 #define ETP_I2C_IAP_VERSION_CMD		0x0110
+#define ETP_I2C_IC_TYPE_P0_CMD		0x0110
 #define ETP_I2C_SET_CMD			0x0300
 #define ETP_I2C_POWER_CMD		0x0307
 #define ETP_I2C_FW_CHECKSUM_CMD		0x030F
@@ -330,7 +331,14 @@ static int elan_i2c_get_sm_version(struct i2c_client *client,
 			return error;
 		}
 		*version = val[0];
-		*ic_type = val[1];
+
+		error = elan_i2c_read_cmd(client, ETP_I2C_IC_TYPE_P0_CMD, val);
+		if (error) {
+			dev_err(&client->dev, "failed to get ic type: %d\n",
+				error);
+			return error;
+		}
+		*ic_type = val[0];
 
 		error = elan_i2c_read_cmd(client, ETP_I2C_NSM_VERSION_CMD,
 					  val);