Input: elan_i2c - clear INT before resetting controller

[ Upstream commit 4b3c7dbb ]

Some old touchpad FWs need to have interrupt cleared before issuing reset
command after updating firmware. We clear interrupt by attempting to read
full report from the controller, and discarding any data read.
Signed-off-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/input/mouse/elan_i2c_i2c.c

@@ -557,7 +557,14 @@ static int elan_i2c_finish_fw_update(struct i2c_client *client,
 	long ret;
 	int error;
 	int len;
-	u8 buffer[ETP_I2C_INF_LENGTH];
+	u8 buffer[ETP_I2C_REPORT_LEN];
+
+	len = i2c_master_recv(client, buffer, ETP_I2C_REPORT_LEN);
+	if (len != ETP_I2C_REPORT_LEN) {
+		error = len < 0 ? len : -EIO;
+		dev_warn(dev, "failed to read I2C data after FW WDT reset: %d (%d)\n",
+			error, len);
+	}
 
 	reinit_completion(completion);
 	enable_irq(client->irq);