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 <h...@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 e9d5086..c314331 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -538,6 +538,15 @@ 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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