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Input: melfas_mip4 - ensure that device is present

PATCH New Dmitry Torokhov 1 participant 1 message Mar 27, 2017

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Dmitry Torokhov

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PATCH 1/1 Input: melfas_mip4 - ensure that device is present

Try a quick read from the device in mip4_query_device() to make sure that the device is there, as we do not consider failures to retrieve product name or resolution fatal.

Signed-off-by Dmitry Torokhov <[email protected]>
---
 drivers/input/touchscreen/melfas_mip4.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
drivers/input/touchscreen/melfas_mip4.c +11 -0
index 703d7f983d0a..05108c2fea93 100644
@@ -253,10 +253,21 @@ static int mip4_get_fw_version(struct mip4_ts *ts)
  */
 static int mip4_query_device(struct mip4_ts *ts)
 {
+	union i2c_smbus_data dummy;
 	int error;
 	u8 cmd[2];
 	u8 buf[14];
 
+	/*
+	 * Make sure there is something at this address as we do not
+	 * consider subsequent failures as fatal.
+	 */
+	if (i2c_smbus_xfer(ts->client->adapter, ts->client->addr,
+			   0, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) {
+		dev_err(&ts->client->dev, "nothing at this address\n");
+		return -ENXIO;
+	}
+
 	/* Product name */
 	cmd[0] = MIP4_R0_INFO;
 	cmd[1] = MIP4_R1_INFO_PRODUCT_NAME;
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Dmitry