Re: [PATCH v4] staging: iio: ad5933: Correct settling cycles encoding per datasheet

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 19 Apr 2025 21:30:09 -0400
Gabriel Shahrouzi <gshahrouzi@gmail.com> wrote:

> The AD5933 datasheet (Table 13) lists the maximum cycles to be 0x7FC
> (2044).
> 
> Clamp the user input to the maximum effective value of 0x7FC cycles.
> 
> Fixes: f94aa354d676 ("iio: impedance-analyzer: New driver for AD5933/4 Impedance Converter, Network Analyzer")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
I'm taking this the slow path as it has been wrong a very long time
and there is a lot of churn on IIO staging drivers right now so we may
have other stuff that I don't want to delay building on top of this.

Applied to the togreg branch of iio.git and pushed out as testing.

Jonathan

> ---
> Changes in v4:
> 	- Provide clear git body description.
> Changes in v3:
> 	- Only include fix (remove refactoring which will be its own
> 	  separate patch).
> Changes in v2:
>         - Fix spacing in comment around '+'.
>         - Define mask and values for settling cycle multipliers.
> ---
>  drivers/staging/iio/impedance-analyzer/ad5933.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
> index d5544fc2fe989..f8fcc10ea8150 100644
> --- a/drivers/staging/iio/impedance-analyzer/ad5933.c
> +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
> @@ -411,7 +411,7 @@ static ssize_t ad5933_store(struct device *dev,
>  		ret = ad5933_cmd(st, 0);
>  		break;
>  	case AD5933_OUT_SETTLING_CYCLES:
> -		val = clamp(val, (u16)0, (u16)0x7FF);
> +		val = clamp(val, (u16)0, (u16)0x7FC);
>  		st->settling_cycles = val;
>  
>  		/* 2x, 4x handling, see datasheet */