[PATCH v4 1/8] iio: adc: stm32-adc: fix channel sampling time init

[Jonathan Cameron]

On Wed, 12 Oct 2022 16:21:58 +0200
Olivier Moysan <olivier.moysan at foss.st.com> wrote:

> Fix channel init for ADC generic channel bindings.
> In generic channel initialization, stm32_adc_smpr_init() is called to
> initialize channel sampling time. The "st,min-sample-time-ns" property
> is an optional property. If it is not defined, stm32_adc_smpr_init() is
> currently skipped.
> However stm32_adc_smpr_init() must always be called, to force a minimum
> sampling time for the internal channels, as the minimum sampling time is
> known. Make stm32_adc_smpr_init() call unconditional.
> 
> Fixes: 796e5d0b1e9b ("iio: adc: stm32-adc: use generic binding for sample-time")
> Signed-off-by: Olivier Moysan <olivier.moysan at foss.st.com>

So I'm crossing my fingers a little that this fix and the rest of the series can
go through different paths - looks like it should be clean.

Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/stm32-adc.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 6256977eb7f7..3cda529f081d 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -2086,18 +2086,19 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
>  		stm32_adc_chan_init_one(indio_dev, &channels[scan_index], val,
>  					vin[1], scan_index, differential);
>  
> +		val = 0;
>  		ret = fwnode_property_read_u32(child, "st,min-sample-time-ns", &val);
>  		/* st,min-sample-time-ns is optional */
> -		if (!ret) {
> -			stm32_adc_smpr_init(adc, channels[scan_index].channel, val);
> -			if (differential)
> -				stm32_adc_smpr_init(adc, vin[1], val);
> -		} else if (ret != -EINVAL) {
> +		if (ret && ret != -EINVAL) {
>  			dev_err(&indio_dev->dev, "Invalid st,min-sample-time-ns property %d\n",
>  				ret);
>  			goto err;
>  		}
>  
> +		stm32_adc_smpr_init(adc, channels[scan_index].channel, val);
> +		if (differential)
> +			stm32_adc_smpr_init(adc, vin[1], val);
> +
>  		scan_index++;
>  	}
>