diff --git a/arch/arm/src/stm32/stm32f20xxx_rcc.c b/arch/arm/src/stm32/stm32f20xxx_rcc.c
index a45241ed85b..ad71714a803 100644
--- a/arch/arm/src/stm32/stm32f20xxx_rcc.c
+++ b/arch/arm/src/stm32/stm32f20xxx_rcc.c
@@ -195,7 +195,13 @@ static inline void rcc_enableahb1(void)
 #ifdef CONFIG_STM32_OTGHS
   /* USB OTG HS */
 
+#ifndef BOARD_DISABLE_USBOTG_HSULPI
+  /* Enable clocking for OTG and external PHY */
+
   regval |= (RCC_AHB1ENR_OTGHSEN | RCC_AHB1ENR_OTGHSULPIEN);
+#else
+  regval |= (RCC_AHB1ENR_OTGHSEN);
+#endif
 #endif
 
   putreg32(regval, STM32_RCC_AHB1ENR);   /* Enable peripherals */
diff --git a/configs/photon/include/board.h b/configs/photon/include/board.h
index ac5faed041e..efce6731152 100644
--- a/configs/photon/include/board.h
+++ b/configs/photon/include/board.h
@@ -146,6 +146,10 @@
 #define STM32_APB2_TIM10_CLKIN  (2*STM32_PCLK2_FREQUENCY)
 #define STM32_APB2_TIM11_CLKIN  (2*STM32_PCLK2_FREQUENCY)
 
+/* USB OTG HS definitions ***********************************************************/
+/* Do not enable external PHY clock or OTG_HS module will not work */
+#define BOARD_DISABLE_USBOTG_HSULPI 1
+
 /* Alternate function pin selections ************************************************/
 /* UART1 */