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| Started by | Andreas Klinger <ak@it-klinger.de> |
|---|---|
| First post | 2017-04-10 19:10 +0200 |
| Last post | 2017-04-14 16:20 +0200 |
| Articles | 4 — 4 participants |
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[PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Andreas Klinger <ak@it-klinger.de> - 2017-04-10 19:10 +0200
Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Linus Walleij <linus.walleij@linaro.org> - 2017-04-11 09:50 +0200
Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Matt Ranostay <matt.ranostay@konsulko.com> - 2017-04-12 02:00 +0200
Re: [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation Jonathan Cameron <jic23@kernel.org> - 2017-04-14 16:20 +0200
| From | Andreas Klinger <ak@it-klinger.de> |
|---|---|
| Date | 2017-04-10 19:10 +0200 |
| Subject | [PATCH v2] IIO: bmp280-core.c: fix error in humidity calculation |
| Message-ID | <tuKZd-3CL-61@gated-at.bofh.it> |
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 --
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| From | Linus Walleij <linus.walleij@linaro.org> |
|---|---|
| Date | 2017-04-11 09:50 +0200 |
| Message-ID | <tuYIN-42a-5@gated-at.bofh.it> |
| In reply to | #1620397 |
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
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| From | Matt Ranostay <matt.ranostay@konsulko.com> |
|---|---|
| Date | 2017-04-12 02:00 +0200 |
| Message-ID | <tvdRw-5mf-1@gated-at.bofh.it> |
| In reply to | #1620397 |
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 > > > --
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| From | Jonathan Cameron <jic23@kernel.org> |
|---|---|
| Date | 2017-04-14 16:20 +0200 |
| Message-ID | <twaeR-261-11@gated-at.bofh.it> |
| In reply to | #1621700 |
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 >> >> >> --
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