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

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 4 Dec 2019 12:13:03 +0100
Couret Charles-Antoine <charles-antoine.couret@essensium.com> wrote:

> 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>
Great thanks.

Applied to the fixes-togreg branch of iio.git.  I've also marked it for stable.

Thanks,

Jonathan

> 
> Regards,
> 
> Charles-Antoine COuret
>