Re: [PATCH 08/10] iio: dac: ad5686: fix input raw value check

[Jonathan Cameron]

On Sun, 26 Apr 2026 09:38:09 +0100
Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@xxxxxxxxxx> wrote:

> From: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
> 
> Use in_range() to fix range check for input raw value, which is off by
> one, i.e., for a 10-bit DAC the max valid value is 1023, but 1 << 10
> equals 1024, which passes the previous check, allowing an out-of-range
> write. The issue exists since the ad5686 driver was first introduced.
> 
> Fixes: c2f37c8dcadc ("iio: dac: New driver for AD5686R, AD5685R, AD5684R Digital to analog converters")
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
> ---
>  drivers/iio/dac/ad5686.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
> index 040a24c62c9a..ab498ec2ed5c 100644
> --- a/drivers/iio/dac/ad5686.c
> +++ b/drivers/iio/dac/ad5686.c
> @@ -186,7 +186,7 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -		if (val > (1 << chan->scan_type.realbits) || val < 0)
> +		if (!in_range(val, 0, 1 << chan->scan_type.realbits))
>  			return -EINVAL;
Fix to >= rather than in_range()

Using in_range when we have a start of 0 is overly complex.

>  
>  		return st->write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
>