From 66b7289ee75653f6024ca3b9c0bdff96fe0bc046 Mon Sep 17 00:00:00 2001
From: guozhanxin <guozhanxin@rt-thread.com>
Date: Tue, 15 Jun 2021 18:29:58 +0800
Subject: [PATCH] [update] usleep supports calling in interrupts.

---
 components/libc/compilers/common/unistd.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/components/libc/compilers/common/unistd.c b/components/libc/compilers/common/unistd.c
index 6c81fc7662..4385643f31 100644
--- a/components/libc/compilers/common/unistd.c
+++ b/components/libc/compilers/common/unistd.c
@@ -55,7 +55,14 @@ RTM_EXPORT(sleep);
 
 int usleep(useconds_t usec)
 {
-    rt_thread_mdelay(usec / 1000u);
+    if (rt_thread_self() != RT_NULL)
+    {
+        rt_thread_mdelay(usec / 1000u);
+    }
+    else
+    {
+        rt_hw_us_delay(usec / 1000u);
+    }
     rt_hw_us_delay(usec % 1000u);
     return 0;
 }