FAILED: patch "[PATCH] iio: adc: stm32: fix a current leak by resetting pcsel before" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f711f28e71e965c0d1141c830fa7131b41abbe75 Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <[email protected]>
Date: Fri, 22 Oct 2021 14:19:29 +0200
Subject: [PATCH] iio: adc: stm32: fix a current leak by resetting pcsel before
disabling vdda

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.

index 6245434f8377..60f2ccf7e342 100644
@@ -1117,6 +1117,7 @@ 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);
 	stm32_adc_int_ch_disable(adc);
 	stm32h7_adc_enter_pwr_down(adc);