ADC's internal VREF and DMA

[pfayolle]

Hello,

I am using an STM32L4R9 to measure 4 external channels connected to the internal ADC. The ADC is triggered by a timer (through a custom patch of adc_stm32.c) and values are moved using DMA.
I want to correct those values using the VREF internal channel of the ADC (as explained in the specification RM0432 §21.4.34), and in order to do that I have to enable the VREFINT channel.

This is how it is done in the stm32-vref sensor:

zephyr/drivers/sensor/st/stm32_vref/stm32_vref.c

Lines 61 to 63 in 3ea2951

	path = LL_ADC_GetCommonPathInternalCh(__LL_ADC_COMMON_INSTANCE(data->adc_base));
	LL_ADC_SetCommonPathInternalCh(__LL_ADC_COMMON_INSTANCE(data->adc_base),
	LL_ADC_PATH_INTERNAL_VREFINT | path);

The stm32-vref sensor does this right before a synchronous ADC read and disables the VREF channel right after. As I use DMA to get the VREF value for each of my samples, I cannot use the stm32-vref sensor.

So my question is: what is the proper way in my case to enable the VREF internal channel ?

Thanks in advance