Re: [PATCH v3 04/15] iio: adc: stm32-adc: manage characterization voltage diversity

[Joshua Crofts <joshua.crofts1@gmail.com>]

On Wed, 30 Sep 2026 16:18:25 +0200
Fabrice Gasnier <fabrice.gasnier@foss.st.com> wrote:

> From: Olivier Moysan <olivier.moysan@foss.st.com>
> 
> The characterization voltage used to calibrate vrefint depends
> on SoC family. Add vref_charac_mv field in stm32_adc_cfg structure
> to store the characterization voltage for each SoC, and use it
> in Vref computation formula.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
> ---
> Changes in v2:
> - Andy's review comments: rename variable to vref_charac_mv (unit suffix).
>   Drop the const attribute.
> ---
>  drivers/iio/adc/stm32-adc.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 600f975f1d7b..fa46803d54be 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -43,7 +43,6 @@
>  #define STM32_ADC_TIMEOUT_US		100000
>  #define STM32_ADC_TIMEOUT	(msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
>  #define STM32_ADC_HW_STOP_DELAY_MS	100
> -#define STM32_ADC_VREFINT_VOLTAGE	3300
>  
>  #define STM32_DMA_BUFFER_SIZE		PAGE_SIZE
>  
> @@ -211,6 +210,7 @@ struct stm32_adc;
>   * @set_ovs:		routine to set oversampling configuration
>   * @smp_cycles:		programmable sampling time (ADC clock cycles)
>   * @ts_int_ch:		pointer to array of internal channels minimum sampling time in ns
> + * @vref_charac_mv:	Vref characterization voltage used to measure vrefint calibration value
>   */
>  struct stm32_adc_cfg {
>  	const struct stm32_adc_regspec	*regs;
> @@ -230,6 +230,7 @@ struct stm32_adc_cfg {
>  	void (*set_ovs)(struct iio_dev *indio_dev, u32 ovs_idx);
>  	const unsigned int *smp_cycles;
>  	const unsigned int *ts_int_ch;
> +	int vref_charac_mv;

Case-sensitive units if it's SI is preferred in IIO, therefore *_mV.
(checkpatch warns against this, but just ignore it).

-- 
Kind regards,
Joshua Crofts