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[PATCH v3 4/8] drivers:input:tsc2007: check for presence and power down tsc2007 during probe

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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>
---
 drivers/input/touchscreen/tsc2007.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index 559cbc6..3ddc31e 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -657,6 +657,15 @@ static int tsc2007_probe(struct i2c_client *client,
 
 	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);
+		iio_device_unregister(indio_dev);
+		return err;	/* usually, chip does not respond */
+	}
+
 	err = input_register_device(input_dev);
 	if (err) {
 		dev_err(&client->dev,
-- 
2.7.3

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[PATCH v3 0/8] drivers: touchscreen: tsc2007 and ads7846/tsc2046 improvements (use common touchscreen bindings, pre-calibration, spi fix and provide iio raw values) "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-09-23 14:50 +0200
  [PATCH v3 7/8] drivers:input:ads7846(+tsc2046): fix spi module table "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-09-23 14:50 +0200
  [PATCH v3 4/8] drivers:input:tsc2007: check for presence and power down tsc2007 during probe "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-09-23 14:50 +0200
  [PATCH v3 8/8] DT:omap3+ads7846: use new common touchscreen bindings "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-09-23 14:50 +0200
  [PATCH v3 6/8] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-09-23 14:50 +0200
    Re: [PATCH v3 6/8] drivers:input:ads7846(+tsc2046): add new common  binding names, pre-calibration and flipping Rob Herring <robh@kernel.org> - 2016-09-24 01:00 +0200

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