Re: [PATCH 2/3] iio: adc: ad7768-1: prevent one-shot mode with wideband filter

["Nuno Sá" <noname.nuno@gmail.com>]

On Sat, 2026-01-31 at 22:35 -0300, Jonathan Santos wrote:
> The AD7768-1 datasheet specifies that the wideband low ripple FIR filter
> is only available in continuous conversion mode and should not be used
> with one-shot mode to avoid malfunction and incorrect data.
> 
> Add filter type checks in ad7768_scan_direct() to skip one-shot mode
> switching when wideband filter is configured.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
>  drivers/iio/adc/ad7768-1.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 8d39b71703ae..374614ea97ac 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -463,14 +463,17 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
>  	struct ad7768_state *st = iio_priv(indio_dev);
>  	int readval, ret;
>  
> -	ret = ad7768_set_mode(st, AD7768_ONE_SHOT);
> -	if (ret < 0)
> -		return ret;
> +	/* Wideband filter is not available in One-Shot conversion mode */
> +	if (st->filter_type != AD7768_FILTER_WIDEBAND) {
> +		ret = ad7768_set_mode(st, AD7768_ONE_SHOT);
> +		if (ret < 0)
> +			return ret;
>  
> -	/* One-shot mode requires a SYNC pulse to generate a new sample */
> -	ret = ad7768_send_sync_pulse(st);
> -	if (ret)
> -		return ret;
> +		/* One-shot mode requires a SYNC pulse to generate a new sample */
> +		ret = ad7768_send_sync_pulse(st);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	reinit_completion(&st->completion);
>  
> @@ -496,9 +499,11 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
>  	 * Any SPI configuration of the AD7768-1 can only be
>  	 * performed in continuous conversion mode.
>  	 */
> -	ret = ad7768_set_mode(st, AD7768_CONTINUOUS);
> -	if (ret < 0)
> -		return ret;
> +	if (st->filter_type != AD7768_FILTER_WIDEBAND) {
> +		ret = ad7768_set_mode(st, AD7768_CONTINUOUS);
> +		if (ret < 0)
> +			return ret;
> +	}


So the idea is to still have continuous mode running and get the latest sample after
we do reinit_completion()? If that's the case, why do we have the one shot logic? Does
it bring that much added value? Asking because I'm just wondering we could just let
it in continuous mode all the time.

This also sounds like a fix so maybe a Fixes tag?

- Nuno Sá