Re: [PATCH 1/4] iio: adc: mcp320x: add masking of unknown bits

[Jonathan Cameron <jic23@kernel.org>]

On 15/07/15 19:12, Hartmut Knaack wrote:
> Andrea Galbusera schrieb am 14.07.2015 um 15:36:
>> According to the datasheet, the 2 MSBs for parts 3001 and 3201 are
>> unspecified and should be masked out
>>
> 
> Hi,
> since resolution is already set, better make it more generic by applying
> the mask in _read_raw like this:
> 
> *val = ret & GENMASK(adc->chip_info->resolution - 1, 0);
> 
> Thanks,
> Hartmut
Agreed, that would be cleaner.
> 
>> Signed-off-by: Andrea Galbusera <gizero@gmail.com>
>> ---
>>
>> This was already suggested but for some reason got lost during review of a
>> previous patch. See http://marc.info/?l=linux-iio&m=140748835509583&w=2
>> and following discussion
>>
>>  drivers/iio/adc/mcp320x.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iio/adc/mcp320x.c b/drivers/iio/adc/mcp320x.c
>> index 8d9c9b9..0673ee7 100644
>> --- a/drivers/iio/adc/mcp320x.c
>> +++ b/drivers/iio/adc/mcp320x.c
>> @@ -114,13 +114,13 @@ static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
>>  
>>  	switch (device_index) {
>>  	case mcp3001:
>> -		return (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3);
>> +		return ((adc->rx_buf[0] & 0x1f) << 5 | adc->rx_buf[1] >> 3);
>>  	case mcp3002:
>>  	case mcp3004:
>>  	case mcp3008:
>>  		return (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6);
>>  	case mcp3201:
>> -		return (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1);
>> +		return ((adc->rx_buf[0] & 0x1f) << 7 | adc->rx_buf[1] >> 1);
>>  	case mcp3202:
>>  	case mcp3204:
>>  	case mcp3208:
>>
> 
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