Re: [PATCH v2 3/4] staging:iio:ad5933: Report temperature as raw value

[Jonathan Cameron <jic23@kernel.org>]

On 27/09/14 10:52, Jonathan Cameron wrote:
> On 25/09/14 15:27, Lars-Peter Clausen wrote:
>> We shouldn't be doing the unit conversion in kernel space. Just report the
>> raw value for the property and the scale. Userspace can do the conversion if
>> necessary.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> Technically you are allowed to do this under the ABI so I'm a little dubious about
> this one except in that the driver has broken for some time an no one has
> noticed hence this is unlikely to cause too many problems!
> 
> Will need to hold this anyway until after the fixes have gone through..
Applied
> 
>> ---
>> Changes from v1:
>> 	* Slightly restructured error path to make it clear that the mutex is
>> 	  only unlocked when it was locked before.
>> ---
>>  drivers/staging/iio/impedance-analyzer/ad5933.c | 20 ++++++++++----------
>>  1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
>> index b6bd609..95b17c5 100644
>> --- a/drivers/staging/iio/impedance-analyzer/ad5933.c
>> +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
>> @@ -113,7 +113,8 @@ static const struct iio_chan_spec ad5933_channels[] = {
>>  		.type = IIO_TEMP,
>>  		.indexed = 1,
>>  		.channel = 0,
>> -		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +			BIT(IIO_CHAN_INFO_SCALE),
>>  		.address = AD5933_REG_TEMP_DATA,
>>  		.scan_index = -1,
>>  		.scan_type = {
>> @@ -520,12 +521,11 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
>>  {
>>  	struct ad5933_state *st = iio_priv(indio_dev);
>>  	__be16 dat;
>> -	int ret = -EINVAL;
>> +	int ret;
>>  
>> -	mutex_lock(&indio_dev->mlock);
>>  	switch (m) {
>>  	case IIO_CHAN_INFO_RAW:
>> -	case IIO_CHAN_INFO_PROCESSED:
>> +		mutex_lock(&indio_dev->mlock);
>>  		if (iio_buffer_enabled(indio_dev)) {
>>  			ret = -EBUSY;
>>  			goto out;
>> @@ -543,16 +543,16 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
>>  		if (ret < 0)
>>  			goto out;
>>  		mutex_unlock(&indio_dev->mlock);
>> -		ret = be16_to_cpu(dat);
>> -		/* Temp in Milli degrees Celsius */
>> -		if (ret < 8192)
>> -			*val = ret * 1000 / 32;
>> -		else
>> -			*val = (ret - 16384) * 1000 / 32;
>> +		*val = sign_extend32(be16_to_cpu(dat), 13);
>>  
>>  		return IIO_VAL_INT;
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*val = 1000;
>> +		*val2 = 5;
>> +		return IIO_VAL_FRACTIONAL_LOG2;
>>  	}
>>  
>> +	return -EINVAL;
>>  out:
>>  	mutex_unlock(&indio_dev->mlock);
>>  	return ret;
>>
> --
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