On Fri, 20 Apr 2018 21:31:48 +0200
David Veenstra <davidjulianveenstra@xxxxxxxxx> wrote:
> A fractional scaling factor of approximately 2 * Pi / (2^12 -1) is added,
> to scale the 12-bits angular position to radians.
>
> Signed-off-by: David Veenstra <davidjulianveenstra@xxxxxxxxx>
> ---
> Changes in v2:
> - This patch replaces the patch that changed the
> the channel for angular position to inclination
> channel.
>
> drivers/staging/iio/resolver/ad2s1200.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c
> index 6c56257be3b1..4f5dd28b174a 100644
> --- a/drivers/staging/iio/resolver/ad2s1200.c
> +++ b/drivers/staging/iio/resolver/ad2s1200.c
> @@ -71,6 +71,17 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
> switch (m) {
> case IIO_CHAN_INFO_SCALE:
> switch (chan->type) {
> + case IIO_ANGL:
> + /*
> + * 2 * Pi / (2^12 - 1) ~= 2 * 103993 / (33102 * 0xFFF)
> + *
> + * Since there only fit 3 whole radians in 360 degrees,
> + * usage of iio_convert_raw_to_processed for this
> + * channel will be highly inaccurate.
> + */
> + *val = 103993;
> + *val2 = 16551 * 0xFFF;
> + return IIO_VAL_FRACTIONAL;
Again, use IIO_VAL_INT_PLUS_MICRO and specify it as a decimal. There is
no need to jump through these hoops when we are unlikely to have any users
that need to keep to integer only maths.
Thanks,
Jonathan
> case IIO_ANGL_VEL:
> /*
> * 2 * Pi ~= 2 * 103993 / 33102
> @@ -133,6 +144,7 @@ static const struct iio_chan_spec ad2s1200_channels[] = {
> .indexed = 1,
> .channel = 0,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> }, {
> .type = IIO_ANGL_VEL,
> .indexed = 1,
--
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