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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     "H. Nikolaus Schaller" <hns@goldelico.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 001/219] Input: tsc2007 - check for presence
 and power down tsc2007 during probe
Thread-Topic: [PATCH AUTOSEL for 4.9 001/219] Input: tsc2007 - check for
 presence and power down tsc2007 during probe
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Date:   Sat, 3 Mar 2018 22:27:55 +0000
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From: "H. Nikolaus Schaller" <hns@goldelico.com>

[ Upstream commit 934df23171e7c5b71d937104d4957891c39748ff ]

1. check if chip is really present and don't succeed if it isn't.
2. if it succeeds, power down the chip until accessed

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/input/touchscreen/tsc2007.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscree=
n/tsc2007.c
index 5d0cd51c6f41..a4b7b4c3d27b 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -455,6 +455,14 @@ static int tsc2007_probe(struct i2c_client *client,
=20
 	tsc2007_stop(ts);
=20
+	/* power down the chip (TSC2007_SETUP does not ACK on I2C) */
+	err =3D tsc2007_xfer(ts, PWRDOWN);
+	if (err < 0) {
+		dev_err(&client->dev,
+			"Failed to setup chip: %d\n", err);
+		return err;	/* usually, chip does not respond */
+	}
+
 	err =3D input_register_device(input_dev);
 	if (err) {
 		dev_err(&client->dev,
--=20
2.14.1