* [PATCH] iio: bmp280: fix compensation of humidity
@ 2020-04-27 14:00 Andreas Klinger
2020-04-27 15:12 ` Tomasz Duszynski
0 siblings, 1 reply; 2+ messages in thread
From: Andreas Klinger @ 2020-04-27 14:00 UTC (permalink / raw)
To: jic23
Cc: knaack.h, lars, pmeerw, bgolaszewski, linus.walleij, tglx,
allison, linux-iio, linux-kernel
Output of humidity compensation is limited to the range between 0 and 100
percent. Add this to the compensation formula as described in the datasheet
chapter 4.2.3.
Signed-off-by: Andreas Klinger <ak@it-klinger.de>
---
drivers/iio/pressure/bmp280-core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 29c209cc1108..ac9ef1b63b07 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -271,6 +271,9 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
+ (s32)2097152) * calib->H2 + 8192) >> 14);
var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)calib->H1) >> 4;
+ var = var < 0 ? 0 : var;
+ var = var > 419430400 ? 419430400 : var;
+
return var >> 12;
};
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iio: bmp280: fix compensation of humidity
2020-04-27 14:00 [PATCH] iio: bmp280: fix compensation of humidity Andreas Klinger
@ 2020-04-27 15:12 ` Tomasz Duszynski
0 siblings, 0 replies; 2+ messages in thread
From: Tomasz Duszynski @ 2020-04-27 15:12 UTC (permalink / raw)
To: Andreas Klinger
Cc: jic23, knaack.h, lars, pmeerw, bgolaszewski, linus.walleij, tglx,
allison, linux-iio, linux-kernel
On Mon, Apr 27, 2020 at 04:00:19PM +0200, Andreas Klinger wrote:
> Output of humidity compensation is limited to the range between 0 and 100
> percent. Add this to the compensation formula as described in the datasheet
> chapter 4.2.3.
>
> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> ---
> drivers/iio/pressure/bmp280-core.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 29c209cc1108..ac9ef1b63b07 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -271,6 +271,9 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
> + (s32)2097152) * calib->H2 + 8192) >> 14);
> var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)calib->H1) >> 4;
>
> + var = var < 0 ? 0 : var;
> + var = var > 419430400 ? 419430400 : var;
> +
Looks that clamp_val() might come in handy here.
> return var >> 12;
> };
>
> --
> 2.20.1
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