[PATCH] iio: adis16201: Correct accelerometer scale factor

[PATCH] iio: adis16201: Correct accelerometer scale factor

[Gabriel Shahrouzi]

The IIO_CHAN_INFO_SCALE previously reported for accelerometer channels
used 0.4624 mg/LSB. This value matches the datasheet specification for
the offset calibration registers (X/YACCL_OFFS_REG, pg 18).

However, the scale should reflect the sensor output data registers
(X/YACCL_OUT, pg 15, Tables 7 & 8), which use 0.4625 mg/LSB. This is
also consistent with the typical sensitivity in Table 1 (1 / 2.162 ≈
0.4625).

Fixes: 57f9386405a2 ("Staging: iio: accel: adis16201: Add comments about units in read_raw()")
Cc: stable@vger.kernel.org
Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
---
 drivers/iio/accel/adis16201.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adis16201.c b/drivers/iio/accel/adis16201.c
index 8601b9a8b8e75..982b33f6eccac 100644
--- a/drivers/iio/accel/adis16201.c
+++ b/drivers/iio/accel/adis16201.c
@@ -133,7 +133,7 @@ static int adis16201_read_raw(struct iio_dev *indio_dev,
 			 * 1 LSB represents 0.244 mg.
 			 */
 			*val = 0;
-			*val2 = IIO_G_TO_M_S_2(462400);
+			*val2 = IIO_G_TO_M_S_2(462500);
 			return IIO_VAL_INT_PLUS_NANO;
 		case IIO_INCLI:
 			*val = 0;
-- 
2.43.0

Re: [PATCH] iio: adis16201: Correct accelerometer scale factor

[Marcelo Schmitt]

LGTM. Minor comments inline.

On 04/19, Gabriel Shahrouzi wrote:
> The IIO_CHAN_INFO_SCALE previously reported for accelerometer channels
> used 0.4624 mg/LSB. This value matches the datasheet specification for
> the offset calibration registers (X/YACCL_OFFS_REG, pg 18).
> 
> However, the scale should reflect the sensor output data registers
> (X/YACCL_OUT, pg 15, Tables 7 & 8), which use 0.4625 mg/LSB. This is
> also consistent with the typical sensitivity in Table 1 (1 / 2.162 ≈
> 0.4625).
> 
> Fixes: 57f9386405a2 ("Staging: iio: accel: adis16201: Add comments about units in read_raw()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
> ---

>  drivers/iio/accel/adis16201.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/adis16201.c b/drivers/iio/accel/adis16201.c
> index 8601b9a8b8e75..982b33f6eccac 100644
> --- a/drivers/iio/accel/adis16201.c
> +++ b/drivers/iio/accel/adis16201.c
> @@ -133,7 +133,7 @@ static int adis16201_read_raw(struct iio_dev *indio_dev,
>  			 * 1 LSB represents 0.244 mg.
Maybe also update the comment?

>  			 */
>  			*val = 0;
> -			*val2 = IIO_G_TO_M_S_2(462400);
> +			*val2 = IIO_G_TO_M_S_2(462500);
If we do the math with more decimal digitis we have 1 / 2.162 == 0.46253469010176
Would it make sense to do 
			*val2 = IIO_G_TO_M_S_2(462535);
?

>  			return IIO_VAL_INT_PLUS_NANO;
>  		case IIO_INCLI:
>  			*val = 0;

Re: [PATCH] iio: adis16201: Correct accelerometer scale factor

[Gabriel Shahrouzi]

On Sat, Apr 19, 2025 at 2:13 PM Marcelo Schmitt
<marcelo.schmitt1@gmail.com> wrote:
>
> LGTM. Minor comments inline.
>
> On 04/19, Gabriel Shahrouzi wrote:
> > The IIO_CHAN_INFO_SCALE previously reported for accelerometer channels
> > used 0.4624 mg/LSB. This value matches the datasheet specification for
> > the offset calibration registers (X/YACCL_OFFS_REG, pg 18).
> >
> > However, the scale should reflect the sensor output data registers
> > (X/YACCL_OUT, pg 15, Tables 7 & 8), which use 0.4625 mg/LSB. This is
> > also consistent with the typical sensitivity in Table 1 (1 / 2.162 ≈
> > 0.4625).
> >
> > Fixes: 57f9386405a2 ("Staging: iio: accel: adis16201: Add comments about units in read_raw()")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
> > ---
>
> >  drivers/iio/accel/adis16201.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/accel/adis16201.c b/drivers/iio/accel/adis16201.c
> > index 8601b9a8b8e75..982b33f6eccac 100644
> > --- a/drivers/iio/accel/adis16201.c
> > +++ b/drivers/iio/accel/adis16201.c
> > @@ -133,7 +133,7 @@ static int adis16201_read_raw(struct iio_dev *indio_dev,
> >                        * 1 LSB represents 0.244 mg.
> Maybe also update the comment?
Good catch. I will update that for v2.
>
> >                        */
> >                       *val = 0;
> > -                     *val2 = IIO_G_TO_M_S_2(462400);
> > +                     *val2 = IIO_G_TO_M_S_2(462500);
> If we do the math with more decimal digitis we have 1 / 2.162 == 0.46253469010176
> Would it make sense to do
>                         *val2 = IIO_G_TO_M_S_2(462535);
> ?
Since the datasheet lists the scale factor as 0.4625 mg, I believe
using *val2 = IIO_G_TO_M_S_2(462500); is correct. However, I'm not
sure so I'll postpone v2.
>
> >                       return IIO_VAL_INT_PLUS_NANO;
> >               case IIO_INCLI:
> >                       *val = 0;