Re: [v2] iio: ad7949: fix channels mixups

[Couret Charles-Antoine <charles-antoine.couret@essensium.com>]

Le 04/12/2019 à 12:06, Jonathan Cameron a écrit :
> On Mon, 2 Dec 2019 16:36:19 +0100
> Couret Charles-Antoine <charles-antoine.couret@essensium.com> wrote:
>
>> Le 02/12/2019 à 15:13, Andrea Merello a écrit :
>>>    drivers/iio/adc/ad7949.c | 22 +++++++++++++++++-----
>>>    1 file changed, 17 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
>>> index 5c2b3446fa4a..2c6f60edb7ce 100644
>>> --- a/drivers/iio/adc/ad7949.c
>>> +++ b/drivers/iio/adc/ad7949.c
>>> @@ -89,6 +89,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
>>>    				   unsigned int channel)
>>>    {
>>>    	int ret;
>>> +	int i;
>>>    	int bits_per_word = ad7949_adc->resolution;
>>>    	int mask = GENMASK(ad7949_adc->resolution, 0);
>>>    	struct spi_message msg;
>>> @@ -100,12 +101,23 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
>>>    		},
>>>    	};
>>>    
>>> -	ret = ad7949_spi_write_cfg(ad7949_adc,
>>> -				   channel << AD7949_OFFSET_CHANNEL_SEL,
>>> -				   AD7949_MASK_CHANNEL_SEL);
>>> -	if (ret)
>>> -		return ret;
>>> +	/*
>>> +	 * 1: write CFG for sample N and read old data (sample N-2)
>>> +	 * 2: if CFG was not changed since sample N-1 then we'll get good data
>>> +	 *    at the next xfer, so we bail out now, otherwise we write something
>>> +	 *    and we read garbage (sample N-1 configuration).
>>> +	 */
>>> +	for (i = 0; i < 2; i++) {
>>> +		ret = ad7949_spi_write_cfg(ad7949_adc,
>>> +					   channel << AD7949_OFFSET_CHANNEL_SEL,
>>> +					   AD7949_MASK_CHANNEL_SEL);
>>> +		if (ret)
>>> +			return ret;
>>> +		if (channel == ad7949_adc->current_channel)
>>> +			break;
>>> +	}
>>>    
>>> +	/* 3: write something and read actual data */
>>>    	ad7949_adc->buffer = 0;
>>>    	spi_message_init_with_transfers(&msg, tx, 1);
>>>    	ret = spi_sync(ad7949_adc->spi, &msg);
>> Signed-off-by: Charles-Antoine Couret <charles-antoine.couret@essensium.com>
> Hi Charles-Antoine,
>
> Why a signed-off-by as opposed to a reviewed-by or similar?
>
> signed-off-by brings some very specific legal implications around Developer
> Certificate of Origin, so is normally just the author plus people involved in
> the path to upstream (maintainers).

Ah sorry, I made the mistake, I wanted to add:

Reviewed-by: Charles-Antoine Couret <charles-antoine.couret@essensium.com>

Regards,

Charles-Antoine COuret