FAILED: patch "[PATCH] iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fb4fbc8904e786537e29329d791147389e1465a2 Mon Sep 17 00:00:00 2001
From: Stephan Gerhold <stephan@gerhold.net>
Date: Mon, 16 Dec 2019 13:41:20 +0100
Subject: [PATCH] iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID

At the moment, attempting to probe a device with ST_LSM6DS3_ID
(e.g. using the st,lsm6ds3 compatible) fails with:

    st_lsm6dsx_i2c 1-006b: unsupported whoami [69]

... even though 0x69 is the whoami listed for ST_LSM6DS3_ID.

This happens because st_lsm6dsx_check_whoami() also attempts
to match unspecified (zero-initialized) entries in the "id" array.
ST_LSM6DS3_ID = 0 will therefore match any entry in
st_lsm6dsx_sensor_settings (here: the first), because none of them
actually have all 12 entries listed in the "id" array.

Avoid this by additionally checking if "name" is set,
which is only set for valid entries in the "id" array.

Note: Although the problem was introduced earlier it did not surface until
commit 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
because ST_LSM6DS3_ID was the first entry in st_lsm6dsx_sensor_settings.

Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
Cc: <stable@vger.kernel.org> # 5.4
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
index a7d40c02ce6b..b921dd9e108f 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -1301,7 +1301,8 @@ static int st_lsm6dsx_check_whoami(struct st_lsm6dsx_hw *hw, int id,
 
 	for (i = 0; i < ARRAY_SIZE(st_lsm6dsx_sensor_settings); i++) {
 		for (j = 0; j < ST_LSM6DSX_MAX_ID; j++) {
-			if (id == st_lsm6dsx_sensor_settings[i].id[j].hw_id)
+			if (st_lsm6dsx_sensor_settings[i].id[j].name &&
+			    id == st_lsm6dsx_sensor_settings[i].id[j].hw_id)
 				break;
 		}
 		if (j < ST_LSM6DSX_MAX_ID)