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

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Date: Sun, 9 Jun 2024 13:18:06 +0200
From: Dimitri Fedrau <dima.fedrau@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Javier Carrasco <javier.carrasco.cruz@...il.com>,
	Li peiyu <579lpy@...il.com>, Lars-Peter Clausen <lars@...afoo.de>,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] iio: humidity: hdc3020: fix hysteresis representation

Am Sun, Jun 09, 2024 at 11:05:58AM +0100 schrieb Jonathan Cameron:
> On Thu, 6 Jun 2024 16:34:39 +0200
> Javier Carrasco <javier.carrasco.cruz@...il.com> wrote:
> 
> > 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@...il.com>
> > > ---
> > > 
> > > 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).
> I fixed that up whilst applying.
> > 
> > > +static int hdc3020_tresh_get_temp(u16 thresh)
> > > +{
> > > +	int temp;
> > > +
> > > +	/*  
> > 
> > 
> > Reviewed-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
> > 
> Applied to the fixes-togreg branch of iio.git and marked for stable.
> 
> Thanks,
> 
> Jonathan
> 
> 

Hi Jonathan,

thanks for fixing this.

Dimitri