[PATCH v5 3/4] iio: imu: st_lsm6dsx: Fix check for invalid samples from FIFO

[Francesco Lavra <flavra@baylibre.com>]

The DRDY_MASK feature implemented in sensor chips marks gyroscope and
accelerometer invalid samples (i.e. samples that have been acquired during
the settling time of sensor filters) with the special values 0x7FFFh,
0x7FFE, and 0x7FFD.
The driver checks FIFO samples against these special values in order to
discard invalid samples; however, it does the check regardless of the type
of samples being processed, whereas this feature is specific to gyroscope
and accelerometer data. This could cause valid samples to be discarded.

Fix the above check so that it takes into account the type of samples being
processed. In st_lsm6dsx_push_tagged_data(), change the type of the data
parameter to __le16 *, to reflect the fact that this function is called
with an aligned data argument and avoid casting to __le16 * when checking
sample values.

Fixes: 960506ed2c69 ("iio: imu: st_lsm6dsx: enable drdy-mask if available")
Signed-off-by: Francesco Lavra <flavra@baylibre.com>
---
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
index 5b28a3ffcc3d..ded9a96076e6 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
@@ -539,14 +539,14 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
 #define ST_LSM6DSX_INVALID_SAMPLE	0x7ffd
 static int
 st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
-			    u8 *data, s64 ts)
+			    __le16 *data, s64 ts)
 {
-	s16 val = le16_to_cpu(*(__le16 *)data);
 	struct st_lsm6dsx_sensor *sensor;
 	struct iio_dev *iio_dev;
 
 	/* invalid sample during bootstrap phase */
-	if (val >= ST_LSM6DSX_INVALID_SAMPLE)
+	if ((tag == ST_LSM6DSX_GYRO_TAG || tag == ST_LSM6DSX_ACC_TAG) &&
+	    (s16)le16_to_cpup(data) >= ST_LSM6DSX_INVALID_SAMPLE)
 		return -EINVAL;
 
 	/*
@@ -670,7 +670,8 @@ int st_lsm6dsx_read_tagged_fifo(struct st_lsm6dsx_hw *hw)
 					reset_ts = true;
 				ts *= hw->ts_gain;
 			} else {
-				st_lsm6dsx_push_tagged_data(hw, tag, iio_buff,
+				st_lsm6dsx_push_tagged_data(hw, tag,
+							    (__le16 *)iio_buff,
 							    ts);
 			}
 		}
-- 
2.39.5