Re: [PATCH v5 3/3] iio: light: ltr390: Calculate 'counts_per_uvi' dynamically

From: Jonathan Cameron
Date: Sat Aug 03 2024 - 10:13:41 EST


On Wed, 31 Jul 2024 12:07:05 +0530
Abhash Jha <abhashkumarjha123@xxxxxxxxx> wrote:

> counts_per_uvi depends on the current value of gain and resolution.
> Hence, we cannot use the hardcoded value 96.
> The `counts_per_uvi` function gives the count based on the current gain
> and resolution (integration time).
>
> Signed-off-by: Abhash Jha <abhashkumarjha123@xxxxxxxxx>
A few additional minor comments inline as you are doing a v6 anyway.

Thanks,

Jonathan

> ---
> drivers/iio/light/ltr390.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/light/ltr390.c b/drivers/iio/light/ltr390.c
> index d3ce43f20..84c084bec 100644
> --- a/drivers/iio/light/ltr390.c
> +++ b/drivers/iio/light/ltr390.c
> @@ -46,6 +46,8 @@
> #define LTR390_UVS_MODE BIT(3)
> #define LTR390_SENSOR_ENABLE BIT(1)
>
> +#define LTR390_FRACTIONAL_PRECISION 100
> +
> /*
> * At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
> * the sensor are equal to 1 UV Index [Datasheet Page#8].
> @@ -120,6 +122,16 @@ static int ltr390_set_mode(struct ltr390_data *data, enum ltr390_mode mode)
> return 0;
> }
>
> +static int ltr390_counts_per_uvi(struct ltr390_data *data)
> +{
> + int orig_gain = 18;
> + int orig_int_time = 400;

add const to these two.

> + int divisor = orig_gain * orig_int_time;
I'd use this orig_gain * orig_int_time inline.

> + int gain = data->gain;

Use this data->gain inline.

> +
> + return DIV_ROUND_CLOSEST(23 * gain * data->int_time_us, 10 * divisor);
> +}
> +
> static int ltr390_read_raw(struct iio_dev *iio_device,
> struct iio_chan_spec const *chan, int *val,
> int *val2, long mask)
> @@ -160,8 +172,8 @@ static int ltr390_read_raw(struct iio_dev *iio_device,
> if (ret < 0)
> return ret;
>
> - *val = LTR390_WINDOW_FACTOR;
> - *val2 = LTR390_COUNTS_PER_UVI;
> + *val = LTR390_WINDOW_FACTOR * LTR390_FRACTIONAL_PRECISION;
> + *val2 = ltr390_counts_per_uvi(data);
> return IIO_VAL_FRACTIONAL;
>
> case IIO_LIGHT: