On Sat, 2019-11-09 at 12:11 +0000, Jonathan Cameron wrote:
> [External]
>
> On Mon, 4 Nov 2019 15:08:12 +0000
> "Ardelean, Alexandru" <alexandru.Ardelean@xxxxxxxxxx> wrote:
>
> > On Sun, 2019-10-13 at 10:47 +0100, jic23@xxxxxxxxxx wrote:
> > > From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > >
> > > Highlighted by sparse:
> > > CHECK drivers/iio/adc/ti-adc084s021.c
> > > drivers/iio/adc/ti-adc084s021.c:79:26: warning: incorrect type in
> > > assignment (different base types)
> > > drivers/iio/adc/ti-adc084s021.c:79:26: expected unsigned short
> > > [unsigned] [short] [usertype] <noident>
> > > drivers/iio/adc/ti-adc084s021.c:79:26: got restricted __be16
> > > <noident>
> > > drivers/iio/adc/ti-adc084s021.c:110:24: warning: cast to restricted
> > > __be16
> > > drivers/iio/adc/ti-adc084s021.c:110:24: warning: cast to restricted
> > > __be16
> > > drivers/iio/adc/ti-adc084s021.c:110:24: warning: cast to restricted
> > > __be16
> > > drivers/iio/adc/ti-adc084s021.c:110:24: warning: cast to restricted
> > > __be16
> > >
> Thanks for looking at this. I'd missed entirely that a void *
> was hiding some more nastiness!
>
> > This one looks a bit tricky.
> > And looks like it could use a bit more cleanup than this.
> > Otherwise sparse may come along and complain about more stuff.
> >
> > One thing that would be good, would be to change:
> >
> > int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
> >
> > to
> >
> > int adc084s021_adc_conversion(struct adc084s021 *adc, __be16 *data, int
> > buf_size) [1]
> >
> >
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > > Cc: Mårten Lindahl <martenli@xxxxxxxx>
> > > ---
> > > drivers/iio/adc/ti-adc084s021.c | 7 ++++---
> > > 1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-
> > > adc084s021.c
> > > index bdedf456ee05..42966f2eb3d8 100644
> > > --- a/drivers/iio/adc/ti-adc084s021.c
> > > +++ b/drivers/iio/adc/ti-adc084s021.c
> > > @@ -68,7 +68,7 @@ static int adc084s021_adc_conversion(struct
> > > adc084s021
> > > *adc, void *data)
> > > {
> > > int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word
> > > */
> > > int ret, i = 0;
> > > - u16 *p = data;
> > > + __be16 *p = data;
> > >
> > > /* Do the transfer */
> > > ret = spi_sync(adc->spi, &adc->message);
> > > @@ -87,6 +87,7 @@ static int adc084s021_read_raw(struct iio_dev
> > > *indio_dev,
> > > {
> > > struct adc084s021 *adc = iio_priv(indio_dev);
> > > int ret;
> > > + __be16 value;
> > >
> > > switch (mask) {
> > > case IIO_CHAN_INFO_RAW:
> > > @@ -101,13 +102,13 @@ static int adc084s021_read_raw(struct iio_dev
> > > *indio_dev,
> > > }
> > >
> > > adc->tx_buf[0] = channel->channel << 3;
> > > - ret = adc084s021_adc_conversion(adc, val);
> > > + ret = adc084s021_adc_conversion(adc, &value);
> >
> > Following [1], this could be called
> > with "adc084s021_adc_conversion(adc,
> > &value, 1)" to make sure it's not doing any stack corruption. I can't
> > tell
> > if this is doing any or not; the code is a bit fuzzy to me.
>
> I'm fairly sure current code is safe as IIO_CHAN_INFO_RAW reads occur
> with protection against buffered mode and when not in buffered mode the
> magic length is 4 which is divided by 2 and has 1 subtracted giving a
> safe value of 1. This dance is ensure there is only one place where
> the length is recorded and avoid recomputing it in
> *_buffer_trigger_handler.
> We could stash it in the private data though for easier to read code.
No idea what's best here.
I am mostly interested in getting the sparse checks up-n-running, so that
we don't have another dance with Greg [as the ones with the ADIS patches].
>
> Agreed that the type change to __be16 * definitely makes sense though.
> Will respin with that.
>
> > The neat part is that memcpy() could be used to then access the data on
> > rx_buf.
>
> We could do that, but as it's not part of the fix really I'd rather leave
> that for another day. Not sure anything stops us doing this whilst doing
> this tidy up even without passing in the size.
Let's leave things here as-is for now.
sparse checks [or any new checks we're adding] feel more important right
now.
Thanks
Alex
>
> Thanks,
>
> Jonathan
>
> >
> > > iio_device_release_direct_mode(indio_dev);
> > > regulator_disable(adc->reg);
> > > if (ret < 0)
> > > return ret;
> > >
> > > - *val = be16_to_cpu(*val);
> > > + *val = be16_to_cpu(value);
> > > *val = (*val >> channel->scan_type.shift) & 0xff;
> > >
> > > return IIO_VAL_INT;
