Re: [PATCH v2 1/2] iio:humidity:si7020: replaced bitmask on humidity values with range check

[Hartmut Knaack <knaack.h@gmx.de>]

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)
>>
> 
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