Re: [PATCH] iio:adc:ti-adc084s021: Endian casting tidy ups.

["Ardelean, Alexandru" <alexandru.Ardelean@analog.com>]

On Sun, 2019-10-13 at 10:47 +0100, jic23@kernel.org wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> 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
> 

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@huawei.com>
> Cc: Mårten Lindahl <martenli@axis.com>
> ---
>  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.

The neat part is that memcpy() could be used to then access the data on
rx_buf.


>  		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;