From 4005f4832fefcf3146244c10cc02bae91a501ade Mon Sep 17 00:00:00 2001
From: Andrew Kozlik <andrew.kozlik@gmail.com>
Date: Wed, 15 Jul 2020 16:49:54 +0200
Subject: [PATCH] core/embed: Set VCP write timeout to 0.

---
 core/embed/firmware/mphalport.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/core/embed/firmware/mphalport.c b/core/embed/firmware/mphalport.c
index 7f364f8b4..9c5c9f141 100644
--- a/core/embed/firmware/mphalport.c
+++ b/core/embed/firmware/mphalport.c
@@ -33,8 +33,9 @@ int mp_hal_stdin_rx_chr(void) {
 
 void mp_hal_stdout_tx_strn(const char *str, size_t len) {
   if (vcp_iface_num >= 0) {
-    int r =
-        usb_vcp_write_blocking(vcp_iface_num, (const uint8_t *)str, len, 500);
+    // The write timeout is set to 0, because otherwise when the VCP receive
+    // buffer on the host gets full, the timeout will block device operation.
+    int r = usb_vcp_write_blocking(vcp_iface_num, (const uint8_t *)str, len, 0);
     (void)r;
   }
 }