From af88e70414061d868a248d1735f26e645d36844c Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Fri, 31 Jan 2020 23:23:56 +1100
Subject: [PATCH] stm32/powerctrl: Reenable PLL3 on H7 MCUs when waking from
 stop mode.

So that USB can work.
---
 ports/stm32/powerctrl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/ports/stm32/powerctrl.c b/ports/stm32/powerctrl.c
index 9619e0ea47..0b26e2aea2 100644
--- a/ports/stm32/powerctrl.c
+++ b/ports/stm32/powerctrl.c
@@ -504,6 +504,13 @@ void powerctrl_enter_stop_mode(void) {
     }
     #endif
 
+    #if defined(STM32H7)
+    // Enable PLL3 for USB
+    RCC->CR |= RCC_CR_PLL3ON;
+    while (!(RCC->CR & RCC_CR_PLL3RDY)) {
+    }
+    #endif
+
     #if defined(STM32L4)
     // Enable PLLSAI1 for peripherals that use it
     RCC->CR |= RCC_CR_PLLSAI1ON;