[PATCH 6.6 094/156] iio: tmag5273: fix temperature offset

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6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Javier Carrasco <javier.carrasco@xxxxxxxxxxxxxx>

commit 3b8157ec4573e304a29b7bced627e144dbc3dfdb upstream.

The current offset has the scale already applied to it. The ABI
documentation defines the offset parameter as "offset to be added
to <type>[Y]_raw prior to scaling by <type>[Y]_scale in order to
obtain value in the <type> units as specified in <type>[Y]_raw
documentation"

The right value is obtained at 0 degrees Celsius by the formula provided
in the datasheet:

T = Tsens_t0 + (Tadc_t - Tadc_t0) / Tadc_res

where:
T = 0 degrees Celsius
Tsens_t0 (reference temperature) = 25 degrees Celsius
Tadc_t0 (16-bit format for Tsens_t0) = 17508
Tadc_res = 60.1 LSB/degree Celsius

The resulting offset is 16005.5, which has been truncated to 16005 to
provide an integer value with a precision loss smaller than the 1-LSB
measurement precision.

Fix the offset to apply its value prior to scaling.

Signed-off-by: Javier Carrasco <javier.carrasco@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/9879beec-05fc-4fc6-af62-d771e238954e@xxxxxxxxxxxxxx
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/iio/magnetometer/tmag5273.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/magnetometer/tmag5273.c
+++ b/drivers/iio/magnetometer/tmag5273.c
@@ -356,7 +356,7 @@ static int tmag5273_read_raw(struct iio_
 	case IIO_CHAN_INFO_OFFSET:
 		switch (chan->type) {
 		case IIO_TEMP:
-			*val = -266314;
+			*val = -16005;
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;






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