Re: [Outreachy kernel] [PATCH] iio: imu: bmi160: bmi160_core: Fix sparse warning

[Alison Schofield <amsfield22@gmail.com>]

On Sun, Oct 02, 2016 at 05:53:08PM +0200, Lars-Peter Clausen wrote:
> On 10/02/2016 07:00 AM, Alison Schofield wrote:
> [...]
> >> ---
> >>  drivers/iio/imu/bmi160/bmi160_core.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi160/bmi160_core.c
> >> index e0251b8..5355507 100644
> >> --- a/drivers/iio/imu/bmi160/bmi160_core.c
> >> +++ b/drivers/iio/imu/bmi160/bmi160_core.c
> >> @@ -398,7 +398,8 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p)
> >>  	struct iio_poll_func *pf = p;
> >>  	struct iio_dev *indio_dev = pf->indio_dev;
> >>  	struct bmi160_data *data = iio_priv(indio_dev);
> >> -	s16 buf[16]; /* 3 sens x 3 axis x s16 + 3 x s16 pad + 4 x s16 tstamp */
> >> +	__le16 buf[16];
> >> +	/* 3 sens x 3 axis x __le16 + 3 x __le16 pad + 4 x __le16 tstamp */
> >>  	int i, ret, j = 0, base = BMI160_REG_DATA_MAGN_XOUT_L;
> >>  	__le16 sample;
> > 
> > Wondering about this option below.  Data was read into an __le16, so that
> > was good diligence on drivers part.  Seems we can use le16_to_cpu() for the
> > conversion into the buf.
> > 
> > --- a/drivers/iio/imu/bmi160/bmi160_core.c
> > +++ b/drivers/iio/imu/bmi160/bmi160_core.c
> > @@ -408,7 +408,7 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p)
> >  				       &sample, sizeof(__le16));
> >  		if (ret < 0)
> >  			goto done;
> > -		buf[j++] = sample;
> > +		buf[j++] = le16_to_cpu(sample);
> >  	}
> 
> This conversion is usually skipped on purpose and delayed until it is
> actually needed by the user. The IIO channel is accordingly marked that it
> will produce LE data.
Thanks Lars.  I knew that for buffers, overlooked it, now I'll know it
better!

So, Sayli, you probably got this from the analysis of the last patch.
In buffered mode, we'll go ahead and return the data in it's 'native'
order.  So, my suggestion to convert it here, is wrong.  Ignore ;)

alisons

>