linux-kernel - [PATCH AUTOSEL for 4.9 033/281] Input: elan_i2c - check if device is there before really probing

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Date:   Mon, 19 Mar 2018 15:58:29 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 033/281] Input: elan_i2c - check if device is
 there before really probing

From: Dmitry Torokhov <dmitry.torokhov@...il.com>

[ Upstream commit c5928551fd41b2eecdad78fa2be2a4a13ed5fde9 ]

Before trying to properly initialize the touchpad and generate bunch of
errors, let's first see it there is anything at the given address. If we
get error, fail silently with -ENXIO.

Reviewed-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/input/mouse/elan_i2c_core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
index c9d491bc85e0..3851d5715772 100644
--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c
@@ -1082,6 +1082,13 @@ static int elan_probe(struct i2c_client *client,
 		return error;
 	}
 
+	/* Make sure there is something at this address */
+	error = i2c_smbus_read_byte(client);
+	if (error < 0) {
+		dev_dbg(&client->dev, "nothing at this address: %d\n", error);
+		return -ENXIO;
+	}
+
 	/* Initialize the touchpad. */
 	error = elan_initialize(data);
 	if (error)
-- 
2.14.1