Re: [PATCH v3] iio: humidity: hdc3020: fix hysteresis representation

[Javier Carrasco]

On 05/06/2024 21:21, Dimitri Fedrau wrote:
> According to the ABI docs hysteresis values are represented as offsets to
> threshold values. Current implementation represents hysteresis values as
> absolute values which is wrong. Nevertheless the device stores them as
> absolute values and the datasheet refers to them as clear thresholds. Fix
> the reading and writing of hysteresis values by including thresholds into
> calculations. Hysteresis values that result in threshold clear values
> that are out of limits will be truncated.
> 
> To check that the threshold clear values are correct, registers are read
> out using i2ctransfer and the corresponding temperature and relative
> humidity thresholds are calculated using the formulas in the datasheet.
> 
> Fixes: 3ad0e7e5f0cb ("iio: humidity: hdc3020: add threshold events support")
> Signed-off-by: Dimitri Fedrau <dima.fedrau@xxxxxxxxx>
> ---
> 
> Changes in V3:
>   - Add missing changes
>   - Remove math.h, already included in math64.h
>   - Drop range comments
>   - Fix typo devide divide
>   - Add empty line before return in hdc3020_write_thresh
>   - Keep hysteresis value when changing the threshold
> 
> ---
>  drivers/iio/humidity/hdc3020.c | 325 +++++++++++++++++++++++++--------
>  1 file changed, 249 insertions(+), 76 deletions(-)
> 
> diff --git a/drivers/iio/humidity/hdc3020.c b/drivers/iio/humidity/hdc3020.c
> index cdc4789213ba..cf00999b826d 100644
> --- a/drivers/iio/humidity/hdc3020.c
> +++ b/drivers/iio/humidity/hdc3020.c
> @@ -19,6 +19,7 @@
>  #include <linux/i2c.h>
>  #include <linux/init.h>
>  #include <linux/interrupt.h>
> +#include <linux/math64.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/pm.h>
> @@ -66,8 +67,10 @@
>  
>  #define HDC3020_CRC8_POLYNOMIAL		0x31
>  
> -#define HDC3020_MIN_TEMP		-40
> -#define HDC3020_MAX_TEMP		125
> +#define HDC3020_MIN_TEMP_MICRO		-39872968
> +#define HDC3020_MAX_TEMP_MICRO		124875639
> +#define HDC3020_MAX_TEMP_HYST_MICRO	164748607
> +#define HDC3020_MAX_HUM_MICRO		99220264
>  
>  struct hdc3020_data {
>  	struct i2c_client *client;
> @@ -368,6 +371,105 @@ static int hdc3020_write_raw(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  }
>  

Nit: "thresh" instead of "tresh" (applies to several lines of your patch).

> +static int hdc3020_tresh_get_temp(u16 thresh)
> +{
> +	int temp;
> +
> +	/*


Reviewed-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>