Re: [PATCH v6 11/16] iio: frequency: ad9910: add digital ramp generator support

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 18 Jun 2026 14:27:27 +0100
Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@kernel.org> wrote:

> From: Rodrigo Alencar <rodrigo.alencar@analog.com>
> 
> Add Digital Ramp Generator channels with destination selection (frequency,
> phase, or amplitude) based on attribute writes, dwell mode control,
> configurable upper/lower limits, step size controlled with rate of change
> config, and step rate controlled as sampling frequency.
> 
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>

End of day, so I'm running out of steam, but one case in here where
I think tweaking an earlier patch will make this one simpler without
costing anything much there.

> ---
>  drivers/iio/frequency/ad9910.c | 345 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 340 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/frequency/ad9910.c b/drivers/iio/frequency/ad9910.c
> index 262702b62738..3fe97aa887c3 100644
> --- a/drivers/iio/frequency/ad9910.c
> +++ b/drivers/iio/frequency/ad9910.c
> @@ -831,22 +1108,62 @@ static int ad9910_write_raw(struct iio_dev *indio_dev,
>  			return -EINVAL;
>  		}
>  	case IIO_CHAN_INFO_RAW:
> -		if (val < 0)
> -			return -EINVAL;
> -
>  		switch (chan->channel) {
>  		case AD9910_CHANNEL_PROFILE_0 ... AD9910_CHANNEL_PROFILE_7:
> +			if (val < 0)
> +				return -EINVAL;

Push it there in the earlier patch.  Which level it is at is a fairly
arbitrary decision in that earlier patch, so let's put it where it ends
up from the start.

> +
>  			tmp32 = chan->channel - AD9910_CHANNEL_PROFILE_0;
>  			tmp64 = FIELD_PREP(AD9910_PROFILE_ST_ASF_MSK,
>  					   min_t(u64, val, AD9910_ASF_MAX));
>  			return ad9910_reg64_update(st, AD9910_REG_PROFILE(tmp32),
>  						   AD9910_PROFILE_ST_ASF_MSK,
>  						   tmp64, true);