* [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check @ 2015-08-22 18:01 Nicola Corna 2015-08-22 21:44 ` Hartmut Knaack 0 siblings, 1 reply; 5+ messages in thread From: Nicola Corna @ 2015-08-22 18:01 UTC (permalink / raw) To: Jonathan Cameron, Hartmut Knaack, Lars-Peter Clausen, Peter Meerwald Cc: linux-iio, Nicola Corna The maximum possible value for the relative humidity is 55575 (100%RH). This value, if shifted right by 2 bits, uses 14 bits and masking it with a 12 bit mask removes 2 meaningful bits. The masking has been replaced with a range check that sets the minimum value at 786 (0%RH) and the maximum at 13894 (100%RH). Signed-off-by: Nicola Corna <nicola@corna.info> --- drivers/iio/humidity/si7020.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c index fa3b809..d27e2f2 100644 --- a/drivers/iio/humidity/si7020.c +++ b/drivers/iio/humidity/si7020.c @@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev, if (ret < 0) return ret; *val = ret >> 2; + /* + * Humidity values can sligthly exceed the 0-100%RH + * range and should be corrected by software + */ if (chan->type == IIO_HUMIDITYRELATIVE) - *val &= GENMASK(11, 0); + clamp_val(*val, 786, 13894); return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: if (chan->type == IIO_TEMP) -- 2.5.0 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check 2015-08-22 18:01 [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check Nicola Corna @ 2015-08-22 21:44 ` Hartmut Knaack 2015-08-22 21:54 ` Hartmut Knaack 0 siblings, 1 reply; 5+ messages in thread From: Hartmut Knaack @ 2015-08-22 21:44 UTC (permalink / raw) To: Nicola Corna, Jonathan Cameron, Lars-Peter Clausen, Peter Meerwald Cc: linux-iio Nicola Corna schrieb am 22.08.2015 um 20:01: > The maximum possible value for the relative humidity is 55575 (100%RH). > This value, if shifted right by 2 bits, uses 14 bits and masking it with > a 12 bit mask removes 2 meaningful bits. > The masking has been replaced with a range check that sets the minimum > value at 786 (0%RH) and the maximum at 13894 (100%RH). > > Signed-off-by: Nicola Corna <nicola@corna.info> Might be discussable, if we want the upper boundary to be rounded down, so we just barely reach 100% rather than slightly exceeding it (in numbers, that is 99,998 vs 100,006). Using 13893 might be the better value. Other than that (and a typo in the comment) looking good, so: Reviewed-by: Hartmut Knaack <knaack.h@gmx.de> > --- > drivers/iio/humidity/si7020.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c > index fa3b809..d27e2f2 100644 > --- a/drivers/iio/humidity/si7020.c > +++ b/drivers/iio/humidity/si7020.c > @@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev, > if (ret < 0) > return ret; > *val = ret >> 2; > + /* > + * Humidity values can sligthly exceed the 0-100%RH Typo: slightly > + * range and should be corrected by software > + */ > if (chan->type == IIO_HUMIDITYRELATIVE) > - *val &= GENMASK(11, 0); > + clamp_val(*val, 786, 13894); > return IIO_VAL_INT; > case IIO_CHAN_INFO_SCALE: > if (chan->type == IIO_TEMP) > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check 2015-08-22 21:44 ` Hartmut Knaack @ 2015-08-22 21:54 ` Hartmut Knaack 2015-08-23 7:41 ` Nicola Corna 0 siblings, 1 reply; 5+ messages in thread From: Hartmut Knaack @ 2015-08-22 21:54 UTC (permalink / raw) To: Nicola Corna, Jonathan Cameron, Lars-Peter Clausen, Peter Meerwald Cc: linux-iio Hartmut Knaack schrieb am 22.08.2015 um 23:44: > Nicola Corna schrieb am 22.08.2015 um 20:01: >> The maximum possible value for the relative humidity is 55575 (100%RH). >> This value, if shifted right by 2 bits, uses 14 bits and masking it with >> a 12 bit mask removes 2 meaningful bits. >> The masking has been replaced with a range check that sets the minimum >> value at 786 (0%RH) and the maximum at 13894 (100%RH). >> >> Signed-off-by: Nicola Corna <nicola@corna.info> > > Might be discussable, if we want the upper boundary to be rounded down, > so we just barely reach 100% rather than slightly exceeding it (in numbers, > that is 99,998 vs 100,006). Using 13893 might be the better value. Other > than that (and a typo in the comment) looking good, so: > Reviewed-by: Hartmut Knaack <knaack.h@gmx.de> On second thought, this is not exactly how clamp_val works. It will return a value between the boundaries, so usage is like this: *val = clamp_val(*val, 786, 13894) If my suggestions are addressed, you can keep my Reviewed-by tag. Thanks, Hartmut >> --- >> drivers/iio/humidity/si7020.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c >> index fa3b809..d27e2f2 100644 >> --- a/drivers/iio/humidity/si7020.c >> +++ b/drivers/iio/humidity/si7020.c >> @@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev, >> if (ret < 0) >> return ret; >> *val = ret >> 2; >> + /* >> + * Humidity values can sligthly exceed the 0-100%RH > > Typo: slightly > >> + * range and should be corrected by software >> + */ >> if (chan->type == IIO_HUMIDITYRELATIVE) >> - *val &= GENMASK(11, 0); >> + clamp_val(*val, 786, 13894); >> return IIO_VAL_INT; >> case IIO_CHAN_INFO_SCALE: >> if (chan->type == IIO_TEMP) >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check 2015-08-22 21:54 ` Hartmut Knaack @ 2015-08-23 7:41 ` Nicola Corna 2015-08-23 11:54 ` Hartmut Knaack 0 siblings, 1 reply; 5+ messages in thread From: Nicola Corna @ 2015-08-23 7:41 UTC (permalink / raw) To: Hartmut Knaack, Jonathan Cameron, Lars-Peter Clausen, Peter Meerwald Cc: linux-iio August 22 2015 11:54 PM, "Hartmut Knaack" <knaack.h@gmx.de> wrote: > Hartmut Knaack schrieb am 22.08.2015 um 23:44: > >> Nicola Corna schrieb am 22.08.2015 um 20:01: >>> The maximum possible value for the relative humidity is 55575 (100%RH). >>> This value, if shifted right by 2 bits, uses 14 bits and masking it with >>> a 12 bit mask removes 2 meaningful bits. >>> The masking has been replaced with a range check that sets the minimum >>> value at 786 (0%RH) and the maximum at 13894 (100%RH). >>> >>> Signed-off-by: Nicola Corna <nicola@corna.info> >> >> Might be discussable, if we want the upper boundary to be rounded down, >> so we just barely reach 100% rather than slightly exceeding it (in numbers, >> that is 99,998 vs 100,006). Using 13893 might be the better value. Other >> than that (and a typo in the comment) looking good, so: >> Reviewed-by: Hartmut Knaack <knaack.h@gmx.de> > > On second thought, this is not exactly how clamp_val works. It will return > a value between the boundaries, so usage is like this: > *val = clamp_val(*val, 786, 13894) > I've tested clamp_val(*val, 786, 13894) and the minimum returned value is 786 while the maximum is 13894; shouldn't the line be like this? *val = clamp_val(*val, 786, 13893) Now the minimum value is 786 (exactly 0%RH), while the maximum (as you pointed out) is 13893 (99,998%RH). Nicola Corna > If my suggestions are addressed, you can keep my Reviewed-by tag. > Thanks, > > Hartmut > >>> --- >>> drivers/iio/humidity/si7020.c | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c >>> index fa3b809..d27e2f2 100644 >>> --- a/drivers/iio/humidity/si7020.c >>> +++ b/drivers/iio/humidity/si7020.c >>> @@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev, >>> if (ret < 0) >>> return ret; >>> *val = ret >> 2; >>> + /* >>> + * Humidity values can sligthly exceed the 0-100%RH >> >> Typo: slightly >> >>> + * range and should be corrected by software >>> + */ >>> if (chan->type == IIO_HUMIDITYRELATIVE) >>> - *val &= GENMASK(11, 0); >>> + clamp_val(*val, 786, 13894); >>> return IIO_VAL_INT; >>> case IIO_CHAN_INFO_SCALE: >>> if (chan->type == IIO_TEMP) >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check 2015-08-23 7:41 ` Nicola Corna @ 2015-08-23 11:54 ` Hartmut Knaack 0 siblings, 0 replies; 5+ messages in thread From: Hartmut Knaack @ 2015-08-23 11:54 UTC (permalink / raw) To: Nicola Corna, Jonathan Cameron, Lars-Peter Clausen, Peter Meerwald Cc: linux-iio Nicola Corna schrieb am 23.08.2015 um 09:41: > August 22 2015 11:54 PM, "Hartmut Knaack" <knaack.h@gmx.de> wrote: >> Hartmut Knaack schrieb am 22.08.2015 um 23:44: >> >>> Nicola Corna schrieb am 22.08.2015 um 20:01: >>>> The maximum possible value for the relative humidity is 55575 (100%RH). >>>> This value, if shifted right by 2 bits, uses 14 bits and masking it with >>>> a 12 bit mask removes 2 meaningful bits. >>>> The masking has been replaced with a range check that sets the minimum >>>> value at 786 (0%RH) and the maximum at 13894 (100%RH). >>>> >>>> Signed-off-by: Nicola Corna <nicola@corna.info> >>> >>> Might be discussable, if we want the upper boundary to be rounded down, >>> so we just barely reach 100% rather than slightly exceeding it (in numbers, >>> that is 99,998 vs 100,006). Using 13893 might be the better value. Other >>> than that (and a typo in the comment) looking good, so: >>> Reviewed-by: Hartmut Knaack <knaack.h@gmx.de> >> >> On second thought, this is not exactly how clamp_val works. It will return >> a value between the boundaries, so usage is like this: >> *val = clamp_val(*val, 786, 13894) >> > > I've tested clamp_val(*val, 786, 13894) and the minimum returned value is 786 > while the maximum is 13894; shouldn't the line be like this? > *val = clamp_val(*val, 786, 13893) > Now the minimum value is 786 (exactly 0%RH), while the maximum (as you pointed > out) is 13893 (99,998%RH). > > Nicola Corna > Using 13893 as top boundary is my preference, although I would not completely object against 13894. So either way would be fine with me. >> If my suggestions are addressed, you can keep my Reviewed-by tag. >> Thanks, >> >> Hartmut >> >>>> --- >>>> drivers/iio/humidity/si7020.c | 6 +++++- >>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c >>>> index fa3b809..d27e2f2 100644 >>>> --- a/drivers/iio/humidity/si7020.c >>>> +++ b/drivers/iio/humidity/si7020.c >>>> @@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev, >>>> if (ret < 0) >>>> return ret; >>>> *val = ret >> 2; >>>> + /* >>>> + * Humidity values can sligthly exceed the 0-100%RH >>> >>> Typo: slightly >>> >>>> + * range and should be corrected by software >>>> + */ >>>> if (chan->type == IIO_HUMIDITYRELATIVE) >>>> - *val &= GENMASK(11, 0); >>>> + clamp_val(*val, 786, 13894); >>>> return IIO_VAL_INT; >>>> case IIO_CHAN_INFO_SCALE: >>>> if (chan->type == IIO_TEMP) >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-08-23 11:54 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2015-08-22 18:01 [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check Nicola Corna 2015-08-22 21:44 ` Hartmut Knaack 2015-08-22 21:54 ` Hartmut Knaack 2015-08-23 7:41 ` Nicola Corna 2015-08-23 11:54 ` Hartmut Knaack
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