From: Dmitry Osipenko digetx@gmail.com
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@vger.kernel.org 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@gmail.com # Asus TF700T Tested-by: Svyatoslav Ryhel clamor95@gmail.com # Asus TF201 Reported-by: Svyatoslav Ryhel clamor95@gmail.com Reviewed-by: Andy Shevchenko Andy.Shevchenko@gmail.com Reviewed-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Dmitry Osipenko digetx@gmail.com Acked-by: Jean-Baptiste Maneyrol jmaneyrol@invensense.com Link: https://lore.kernel.org/r/20210423020959.5023-1-digetx@gmail.com Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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;