From c2e0afdb057ccf4c6440322a1409ec7b94fe16ea Mon Sep 17 00:00:00 2001
From: Karl Palsson <karlp@tweak.net.au>
Date: Fri, 9 Sep 2016 21:35:18 +0000
Subject: [PATCH] stm32: adc-v2: don't try and disable adc powered off

As per ref manual, you're not allowed to attempt to disable the ADC if
it's not presently enabled.

Fixes github issue #654
---
 lib/stm32/common/adc_common_v2.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/stm32/common/adc_common_v2.c b/lib/stm32/common/adc_common_v2.c
index 6d33388b..62e3881a 100644
--- a/lib/stm32/common/adc_common_v2.c
+++ b/lib/stm32/common/adc_common_v2.c
@@ -106,6 +106,10 @@ void adc_power_on(uint32_t adc)
  */
 void adc_power_off_async(uint32_t adc)
 {
+	if (adc_is_power_off(adc)) {
+		return;
+	}
+
 	uint32_t checks = ADC_CR_ADSTART;
 	uint32_t stops = ADC_CR_ADSTP;
 #if defined (ADC_CR_JADSTART)