From cb6289fd8539453107cbfe9f68511f5b6f72e373 Mon Sep 17 00:00:00 2001
From: PaulStoffregen <paul@pjrc.com>
Date: Mon, 27 Aug 2018 10:46:36 -0700
Subject: [PATCH] Avoid USB bug related with O2 optimize

---
 teensy3/usb_dev.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/teensy3/usb_dev.c b/teensy3/usb_dev.c
index 3ac929ce5..e483ae270 100644
--- a/teensy3/usb_dev.c
+++ b/teensy3/usb_dev.c
@@ -45,6 +45,14 @@
 #include "usb_mem.h"
 #include <string.h> // for memset
 
+// This code has a known bug with compiled with -O2 optimization on gcc 5.4.1
+// https://forum.pjrc.com/threads/53574-Teensyduino-1-43-Beta-2?p=186177&viewfull=1#post186177
+#if defined(__MKL26Z64__)
+#pragma GCC optimize ("Os")
+#else
+#pragma GCC optimize ("O3")
+#endif
+
 // buffer descriptor table
 
 typedef struct {