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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, KT Liao <kt.liao@emc.com.tw>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 077/190] Input: elan_i2c - clear INT before resetting controller
Date:   Wed, 11 Apr 2018 20:35:23 +0200
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: KT Liao <kt.liao@emc.com.tw>


[ Upstream commit 4b3c7dbbfff0673e8a89575414b864d8b001d3bb ]

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 |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/input/mouse/elan_i2c_i2c.c
+++ b/drivers/input/mouse/elan_i2c_i2c.c
@@ -557,7 +557,14 @@ static int elan_i2c_finish_fw_update(str
 	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);