From 4896fb1348713344abbd9f692b393b5fdc539bf8 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Fri, 24 Mar 2017 16:50:28 -0700 Subject: [PATCH] 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 --- drivers/input/touchscreen/melfas_mip4.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/input/touchscreen/melfas_mip4.c b/drivers/input/touchscreen/melfas_mip4.c index 703d7f9..05108c2 100644 --- a/drivers/input/touchscreen/melfas_mip4.c +++ b/drivers/input/touchscreen/melfas_mip4.c @@ -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; -- 2.7.4