Messages in this thread | | | Subject | Re: [PATCH] iio: adc: stm32: fix a leak by resetting pcsel before disabling vdda | From | Fabrice Gasnier <> | Date | Mon, 25 Oct 2021 09:43:10 +0200 |
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On 10/24/21 6:07 PM, Jonathan Cameron wrote: > On Fri, 22 Oct 2021 14:38:52 +0200 > Olivier MOYSAN <olivier.moysan@foss.st.com> wrote: > > I'll probably reword the description here as 'leak' tends to mean memory > leak rather than current.
Hi Jonathan,
Yes, please fell free to improve this. I had the same concern, but I haven't found a more suitable description.
> >> Hi Fabrice, >> >> On 10/22/21 2:19 PM, Fabrice Gasnier wrote: >>> Some I/Os are connected to ADC input channels, when the corresponding bit >>> in PCSEL register are set on STM32H7 and STM32MP15. This is done in the >>> prepare routine of stm32-adc driver. >>> There are constraints here, as PCSEL shouldn't be set when VDDA supply >>> is disabled. Enabling/disabling of VDDA supply in done via stm32-adc-core >>> runtime PM routines (before/after ADC is enabled/disabled). >>> >>> Currently, PCSEL remains set when disabling ADC. Later on, PM runtime >>> can disable the VDDA supply. This creates some conditions on I/Os that >>> can start to leak current. >>> So PCSEL needs to be cleared when disabling the ADC. >>> >>> Fixes: 95e339b6e85d ("iio: adc: stm32: add support for STM32H7") >>> > > No line break here as Fixes forms part of the tag block. >
Sorry, will check this next time.
>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com> > > Given timing wrt to being too near merge window, I'll let this it on > list a while longer as it'll be post rc1 material now anyway. > > I can fix the above whilst applying if nothing else comes up.
That's fine for me.
Many thanks, Fabrice > > Jonathan > >>> --- >>> drivers/iio/adc/stm32-adc.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c >>> index 5088de8..e3e7541 100644 >>> --- a/drivers/iio/adc/stm32-adc.c >>> +++ b/drivers/iio/adc/stm32-adc.c >>> @@ -975,6 +975,7 @@ static void stm32h7_adc_unprepare(struct iio_dev *indio_dev) >>> { >>> struct stm32_adc *adc = iio_priv(indio_dev); >>> >>> + stm32_adc_writel(adc, STM32H7_ADC_PCSEL, 0); >>> stm32h7_adc_disable(indio_dev); >>> stm32h7_adc_enter_pwr_down(adc); >>> } >>> >> >> Reviewed-by: Olivier Moysan <olivier.moysan@foss.st.com> >> >> Thanks >> Olivier >
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