diff --git a/arch/arm/src/samd5e5/sam_eic.c b/arch/arm/src/samd5e5/sam_eic.c
index e5740612a4..6d6d6dd0c4 100644
--- a/arch/arm/src/samd5e5/sam_eic.c
+++ b/arch/arm/src/samd5e5/sam_eic.c
@@ -116,7 +116,7 @@ void sam_eic_dumpregs(void)
  * Name: sam_eic_initialize
  *
  * Description:
- *   Initialize the external interrupt controller (EIC).
+ *   Initialize the EIC.  Called one timer during system bring-up.
  *
  * Input Parameters:
  *   None
@@ -153,10 +153,11 @@ int sam_eic_initialize(void)
  * Name: sam_eic_configure
  *
  * Description:
- *   Configure the interrupt edge sensitivity in CONFIGn register of the EIC
+ *   Configure the interrupt edge sensitivity in CONFIGn register of the
+ *   EIC.  The interrupt will be enabled at the EIC (but not at the NVIC).
  *
  * Input Parameters:
- *   eirq    - Pin to be configured
+ *   eirq    - Pin to be configured (0..15)
  *   pinset  - Configuration of the pin
  *
  * Returned Value:
@@ -177,12 +178,12 @@ int sam_eic_configure(uint8_t eirq, port_pinset_t pinset)
       reg = SAM_EIC_CONFIG0;
 
       val = EIC_CONFIG0_SENSE_BOTH(eirq);
-      if (pinset & PORT_INT_RISING)
+      if ((pinset & PORT_INT_RISING) != 0)
         {
           val = EIC_CONFIG0_SENSE_RISE(eirq);
         }
 
-      if (pinset & PORT_INT_FALLING)
+      if ((pinset & PORT_INT_FALLING) != 0)
         {
           val = EIC_CONFIG0_SENSE_FALL(eirq);
         }
@@ -194,12 +195,12 @@ int sam_eic_configure(uint8_t eirq, port_pinset_t pinset)
       reg = SAM_EIC_CONFIG1;
 
       val = EIC_CONFIG1_SENSE_BOTH(eirq);
-      if (pinset & PORT_INT_RISING)
+      if ((pinset & PORT_INT_RISING) != 0)
         {
           val = EIC_CONFIG1_SENSE_RISE(eirq);
         }
 
-      if (pinset & PORT_INT_FALLING)
+      if ((pinset & PORT_INT_FALLING) != 0)
         {
           val = EIC_CONFIG1_SENSE_FALL(eirq);
         }
@@ -221,34 +222,6 @@ int sam_eic_configure(uint8_t eirq, port_pinset_t pinset)
   return OK;
 }
 
-/****************************************************************************
- * Name: sam_eic_irq_enable
- *
- * Description:
- *   Enable an external interrupt.
- *
- * Input Parameters:
- *   irq - SAM_IRQ_EXTINTn IRQ to be enabled
- *
- * Returned Value:
- *   None
- *
- ****************************************************************************/
-
-int sam_eic_irq_enable(int irq)
-{
-  uint32_t config;
-  int eirq = irq - SAM_IRQ_EXTINT0;
-
-  config  = getreg32(SAM_EIC_CONFIG0);
-  config |= EIC_CONFIG0_FILTEN(eirq) | EIC_CONFIG0_SENSE_FALL(eirq);
-  putreg32(config, SAM_EIC_CONFIG0);
-
-  putreg32(EIC_EXTINT(eirq), SAM_EIC_INTENSET);
-  sam_eic_dumpregs();
-  return OK;
-}
-
 /****************************************************************************
  * Name: sam_eic_irq_ack
  *
@@ -256,7 +229,7 @@ int sam_eic_irq_enable(int irq)
  *   Acknowledge receipt of an external interrupt.
  *
  * Input Parameters:
- *   irq - SAM_IRQ_EXTINTn IRQ to be acknowledged
+ *   irq - SAM_IRQ_EXTINTn IRQ to be acknowledged, n=0-15
  *
  * Returned Value:
  *   None
diff --git a/arch/arm/src/samd5e5/sam_eic.h b/arch/arm/src/samd5e5/sam_eic.h
index 722a3c7ce8..54084fa0df 100644
--- a/arch/arm/src/samd5e5/sam_eic.h
+++ b/arch/arm/src/samd5e5/sam_eic.h
@@ -68,7 +68,7 @@ extern "C"
  * Name: sam_eic_initialize
  *
  * Description:
- *   Initialize the EIC
+ *   Initialize the EIC.  Called one timer during system bring-up.
  *
  * Input Parameters:
  *   None
@@ -84,10 +84,11 @@ int sam_eic_initialize(void);
  * Name: sam_eic_configure
  *
  * Description:
- *   Configure the interrupt edge sensitivity in CONFIGn register of the EIC
+ *   Configure the interrupt edge sensitivity in CONFIGn register of the
+ *   EIC.  The interrupt will be enabled at the EIC (but not at the NVIC).
  *
  * Input Parameters:
- *   eirq    - Pin to be configured
+ *   eirq    - Pin to be configured (0..15)
  *   pinset  - Configuration of the pin
  *
  * Returned Value:
@@ -97,22 +98,6 @@ int sam_eic_initialize(void);
 
 int sam_eic_configure(uint8_t eirq, port_pinset_t pinset);
 
-/****************************************************************************
- * Name: sam_eic_irq_enable
- *
- * Description:
- *   Enable a external interrupt.
- *
- * Input Parameters:
- *   irq - SAM_IRQ_EXTINTn IRQ to be enabled
- *
- * Returned Value:
- *   None
- *
- ****************************************************************************/
-
-int sam_eic_irq_enable(int irq);
-
 /****************************************************************************
  * Name: sam_eic_irq_ack
  *
@@ -120,7 +105,7 @@ int sam_eic_irq_enable(int irq);
  *   Acknowledge receipt of an external interrupt.
  *
  * Input Parameters:
- *   irq - SAM_IRQ_EXTINTn IRQ to be acknowledged
+ *   irq - SAM_IRQ_EXTINTn IRQ to be acknowledged, n=0-15
  *
  * Returned Value:
  *   None
diff --git a/configs/metro-m4/include/board.h b/configs/metro-m4/include/board.h
index 98c5047332..ee912bee66 100644
--- a/configs/metro-m4/include/board.h
+++ b/configs/metro-m4/include/board.h
@@ -54,7 +54,7 @@
 /* Clocking *************************************************************************/
 /* Overview
  *
- * Since there is not high speed crystal, we will run from the OSC16M clock source.
+ * Since there is no high speed crystal, we will run from the OSC16M clock source.
  * We will use its default, POR frequency of 4MHz to avoid an additional clock
  * switch.
  *
diff --git a/configs/saml21-xplained/include/board.h b/configs/saml21-xplained/include/board.h
index f63b9d27a2..69307f1873 100644
--- a/configs/saml21-xplained/include/board.h
+++ b/configs/saml21-xplained/include/board.h
@@ -56,7 +56,7 @@
 /* Clocking *************************************************************************/
 /* Overview
  *
- * Since there is not high speed crystal, we will run from the OSC16M clock source.
+ * Since there is no high speed crystal, we will run from the OSC16M clock source.
  * We will use its default, POR frequency of 4MHz to avoid an additional clock
  * switch.
  *