From: Dmitry Osipenko <digetx@xxxxxxxxx>
commit f73c730774d88a14d7b60feee6d0e13570f99499 upstream.
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>
Acked-by: Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210423020959.5023-1-digetx@xxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iio/gyro/mpu3050-core.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/iio/gyro/mpu3050-core.c
+++ b/drivers/iio/gyro/mpu3050-core.c
@@ -270,7 +270,16 @@ static int mpu3050_read_raw(struct iio_d
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
+ * for the "best fit straight line" temperature range
+ * of -30C..85C. The 23000 includes room temperature
+ * offset of +35C, 280 is the precision scale and x is
+ * the 16-bit signed integer reported by hardware.
+ *
+ * Temperature value itself represents temperature of
+ * the sensor die.
+ */
*val = 23000;
return IIO_VAL_INT;
default:
@@ -327,7 +336,7 @@ static int mpu3050_read_raw(struct iio_d
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;
