* [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation
@ 2017-04-10 17:00 Andreas Klinger
2017-04-11 7:45 ` Linus Walleij
2017-04-11 23:59 ` Matt Ranostay
0 siblings, 2 replies; 4+ messages in thread
From: Andreas Klinger @ 2017-04-10 17:00 UTC (permalink / raw)
To: Jonathan Cameron, Matt Ranostay, Linus Walleij, Hartmut Knaack,
Lars-Peter Clausen, Peter Meerwald, Vlad Dogaru, Akinobu Mita,
Wei Yongjun, Aniroop Mathur
Cc: linux-iio, linux-kernel
While calculating the compensation of the humidity there are negative values
interpreted as unsigned because of unsigned variables used. These values as
well as the constants need to be casted to signed as indicated by the
documentation of the sensor.
Changes in v2:
- cast also constants to signed; otherwise calculation is not correct
I removed the Acked-By of Linus Walleij because of another change in the
calculation. Don't know how it should be treated.
Signed-off-by: Andreas Klinger <ak@it-klinger.de>
---
drivers/iio/pressure/bmp280-core.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 4d18826ac63c..d82b788374b6 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -175,11 +175,12 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
}
H6 = sign_extend32(tmp, 7);
- var = ((s32)data->t_fine) - 76800;
- var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
- * (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
- + 2097152) * H2 + 8192) >> 14);
- var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;
+ var = ((s32)data->t_fine) - (s32)76800;
+ var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var))
+ + (s32)16384) >> 15) * (((((((var * H6) >> 10)
+ * (((var * (s32)H3) >> 11) + (s32)32768)) >> 10)
+ + (s32)2097152) * H2 + 8192) >> 14);
+ var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4;
return var >> 12;
};
--
2.1.4
--
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation
2017-04-10 17:00 [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Andreas Klinger
@ 2017-04-11 7:45 ` Linus Walleij
2017-04-11 23:59 ` Matt Ranostay
1 sibling, 0 replies; 4+ messages in thread
From: Linus Walleij @ 2017-04-11 7:45 UTC (permalink / raw)
To: Andreas Klinger
Cc: Jonathan Cameron, Matt Ranostay, Hartmut Knaack,
Lars-Peter Clausen, Peter Meerwald, Vlad Dogaru, Akinobu Mita,
Wei Yongjun, Aniroop Mathur, linux-iio, linux-kernel
On Mon, Apr 10, 2017 at 7:00 PM, Andreas Klinger <ak@it-klinger.de> wrote:
> While calculating the compensation of the humidity there are negative values
> interpreted as unsigned because of unsigned variables used. These values as
> well as the constants need to be casted to signed as indicated by the
> documentation of the sensor.
>
> Changes in v2:
> - cast also constants to signed; otherwise calculation is not correct
>
> I removed the Acked-By of Linus Walleij because of another change in the
> calculation. Don't know how it should be treated.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
You guys do an awesome job at maintaining the sensor code, thanks.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation
2017-04-10 17:00 [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Andreas Klinger
2017-04-11 7:45 ` Linus Walleij
@ 2017-04-11 23:59 ` Matt Ranostay
2017-04-14 14:13 ` Jonathan Cameron
1 sibling, 1 reply; 4+ messages in thread
From: Matt Ranostay @ 2017-04-11 23:59 UTC (permalink / raw)
To: Andreas Klinger
Cc: Jonathan Cameron, Linus Walleij, Hartmut Knaack,
Lars-Peter Clausen, Peter Meerwald, Vlad Dogaru, Akinobu Mita,
Wei Yongjun, Aniroop Mathur, linux-iio, linux-kernel
On Mon, Apr 10, 2017 at 10:00 AM, Andreas Klinger <ak@it-klinger.de> wrote:
> While calculating the compensation of the humidity there are negative values
> interpreted as unsigned because of unsigned variables used. These values as
> well as the constants need to be casted to signed as indicated by the
> documentation of the sensor.
>
> Changes in v2:
> - cast also constants to signed; otherwise calculation is not correct
>
> I removed the Acked-By of Linus Walleij because of another change in the
> calculation. Don't know how it should be treated.
>
> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
> ---
> drivers/iio/pressure/bmp280-core.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 4d18826ac63c..d82b788374b6 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -175,11 +175,12 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
> }
> H6 = sign_extend32(tmp, 7);
>
> - var = ((s32)data->t_fine) - 76800;
> - var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
> - * (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
> - + 2097152) * H2 + 8192) >> 14);
> - var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;
> + var = ((s32)data->t_fine) - (s32)76800;
> + var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var))
> + + (s32)16384) >> 15) * (((((((var * H6) >> 10)
> + * (((var * (s32)H3) >> 11) + (s32)32768)) >> 10)
> + + (s32)2097152) * H2 + 8192) >> 14);
> + var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4;
>
> return var >> 12;
> };
> --
> 2.1.4
>
>
> --
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation
2017-04-11 23:59 ` Matt Ranostay
@ 2017-04-14 14:13 ` Jonathan Cameron
0 siblings, 0 replies; 4+ messages in thread
From: Jonathan Cameron @ 2017-04-14 14:13 UTC (permalink / raw)
To: Matt Ranostay, Andreas Klinger
Cc: Linus Walleij, Hartmut Knaack, Lars-Peter Clausen,
Peter Meerwald, Vlad Dogaru, Akinobu Mita, Wei Yongjun,
Aniroop Mathur, linux-iio, linux-kernel
On 12/04/17 00:59, Matt Ranostay wrote:
> On Mon, Apr 10, 2017 at 10:00 AM, Andreas Klinger <ak@it-klinger.de> wrote:
>> While calculating the compensation of the humidity there are negative values
>> interpreted as unsigned because of unsigned variables used. These values as
>> well as the constants need to be casted to signed as indicated by the
>> documentation of the sensor.
>>
>> Changes in v2:
>> - cast also constants to signed; otherwise calculation is not correct
>>
>> I removed the Acked-By of Linus Walleij because of another change in the
>> calculation. Don't know how it should be treated.
>>
>> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
>
> Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
Applied to the fixes-togreg branch of iio.git and marked for
stable.
Thanks,
Jonathan
>
>> ---
>> drivers/iio/pressure/bmp280-core.c | 11 ++++++-----
>> 1 file changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
>> index 4d18826ac63c..d82b788374b6 100644
>> --- a/drivers/iio/pressure/bmp280-core.c
>> +++ b/drivers/iio/pressure/bmp280-core.c
>> @@ -175,11 +175,12 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
>> }
>> H6 = sign_extend32(tmp, 7);
>>
>> - var = ((s32)data->t_fine) - 76800;
>> - var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
>> - * (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
>> - + 2097152) * H2 + 8192) >> 14);
>> - var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;
>> + var = ((s32)data->t_fine) - (s32)76800;
>> + var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var))
>> + + (s32)16384) >> 15) * (((((((var * H6) >> 10)
>> + * (((var * (s32)H3) >> 11) + (s32)32768)) >> 10)
>> + + (s32)2097152) * H2 + 8192) >> 14);
>> + var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4;
>>
>> return var >> 12;
>> };
>> --
>> 2.1.4
>>
>>
>> --
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-04-10 17:00 [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Andreas Klinger
2017-04-11 7:45 ` Linus Walleij
2017-04-11 23:59 ` Matt Ranostay
2017-04-14 14:13 ` Jonathan Cameron
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