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

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

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).

> 
> Regards,
> Charles-Antoine Couret