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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, "H. Nikolaus Schaller" <hns@goldelico.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 002/241] Input: tsc2007 - check for presence and power down tsc2007 during probe
Date:   Mon, 19 Mar 2018 19:04:27 +0100
Message-Id: <20180319180751.272167310@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/input/touchscreen/tsc2007.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -455,6 +455,14 @@ static int tsc2007_probe(struct i2c_clie
 
 	tsc2007_stop(ts);
 
+	/* power down the chip (TSC2007_SETUP does not ACK on I2C) */
+	err = 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 = input_register_device(input_dev);
 	if (err) {
 		dev_err(&client->dev,