The raw temperature value is a 16-bit signed integer. The sign casting
is missing in the code, which results in a wrong temperature reported
by userspace tools, fix it.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 3904b28efb2c ("iio: gyro: Add driver for the MPU-3050 gyroscope")
Datasheet: https://www.cdiweb.com/datasheets/invensense/mpu-3000a.pdf
Tested-by: Maxim Schwalm <maxim.schwalm@xxxxxxxxx> # Asus TF700T
Tested-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx> # Asus TF201
Reported-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <Andy.Shevchenko@xxxxxxxxx>
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
Changelog:
v2: - Replaced "signed 16bit integer" wording with "16-bit signed integer",
replaced "Link" tag with the "Datasheet" and added "Fixes" tag as was
suggested by Andy Shevchenko.
- Added r-b from Andy Shevchenko and Linus Walleij.
drivers/iio/gyro/mpu3050-core.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
index ac90be03332a..ce9d1d3687f5 100644
--- a/drivers/iio/gyro/mpu3050-core.c
+++ b/drivers/iio/gyro/mpu3050-core.c
@@ -272,7 +272,16 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,
case IIO_CHAN_INFO_OFFSET:
switch (chan->type) {
case IIO_TEMP:
- /* The temperature scaling is (x+23000)/280 Celsius */
+ /*
+ * The temperature scaling is (x+23000)/280 Celsius,
+ * where 23000 includes room temperature offset of
+ * +35C, 280 is the precision scale and x is the 16-bit
+ * signed integer which corresponds to the temperature
+ * range of -40C..85C.
+ *
+ * Temperature value itself represents temperature of
+ * the sensor die.
+ */
*val = 23000;
return IIO_VAL_INT;
default:
@@ -329,7 +338,7 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,
goto out_read_raw_unlock;
}
- *val = be16_to_cpu(raw_val);
+ *val = (s16)be16_to_cpu(raw_val);
ret = IIO_VAL_INT;
goto out_read_raw_unlock;
--
2.30.2
