From bdb60ac2f7310b9687bfe123cc061f2c6ab3b1a1 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Tue, 20 Nov 2018 12:29:37 -0600
Subject: [PATCH] arch/arm/src/stm32/stm32_adc.c:  Very mysterious.  Several
 configurations now fail to build stm32_adc.o.  This chante avoids those build
 failures, yet I see no code changed in recent months that should affect this.
  Any insights anyone?

---
 arch/arm/src/stm32/stm32_adc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/src/stm32/stm32_adc.c b/arch/arm/src/stm32/stm32_adc.c
index dd15c7e0f8f..be75506a38f 100644
--- a/arch/arm/src/stm32/stm32_adc.c
+++ b/arch/arm/src/stm32/stm32_adc.c
@@ -3011,6 +3011,7 @@ static int adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
               return ret;
             }
 
+#ifdef CONFIG_ADC
           if (ch)
             {
               /* Clear fifo */
@@ -3018,6 +3019,7 @@ static int adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
               dev->ad_recv.af_head = 0;
               dev->ad_recv.af_tail = 0;
             }
+#endif
 
           adc_startconv(priv, true);
           break;