4 files changed, 29 insertions, 10 deletions
diff --git a/src/osal/osal.h b/src/osal/osal.h
index 9d11866df..afa3826fc 100644
--- a/src/osal/osal.h
+++ b/src/osal/osal.h
@@ -33,17 +33,24 @@
 
 #include "common/tusb_common.h"
 
-// Return immediately
-#define OSAL_TIMEOUT_NOTIMEOUT     (0)
-// Default timeout
-#define OSAL_TIMEOUT_NORMAL        (10)
-// Wait forever
-#define OSAL_TIMEOUT_WAIT_FOREVER  (UINT32_MAX)
+typedef void (*osal_task_func_t)( void * );
 
+// Timeout
+#define OSAL_TIMEOUT_NOTIMEOUT     (0)          // Return immediately
+#define OSAL_TIMEOUT_NORMAL        (10)         // Default timeout
+#define OSAL_TIMEOUT_WAIT_FOREVER  (UINT32_MAX) // Wait forever
 #define OSAL_TIMEOUT_CONTROL_XFER  OSAL_TIMEOUT_WAIT_FOREVER
 
-typedef void (*osal_task_func_t)( void * );
+// Mutex is required when using a preempted RTOS or MCU has multiple cores
+#if (CFG_TUSB_OS == OPT_OS_NONE) && !TUP_MCU_MULTIPLE_CORE
+  #define OSAL_MUTEX_REQUIRED   0
+  #define OSAL_MUTEX_DEF(_name) uint8_t :0
+#else
+  #define OSAL_MUTEX_REQUIRED   1
+  #define OSAL_MUTEX_DEF(_name) osal_mutex_def_t _name
+#endif
 
+// OS thin implementation
 #if CFG_TUSB_OS == OPT_OS_NONE
   #include "osal_none.h"
 #elif CFG_TUSB_OS == OPT_OS_FREERTOS
diff --git a/src/osal/osal_freertos.h b/src/osal/osal_freertos.h
index 327aa9970..9393d1f26 100644
--- a/src/osal/osal_freertos.h
+++ b/src/osal/osal_freertos.h
@@ -115,7 +115,7 @@ TU_ATTR_ALWAYS_INLINE static inline bool osal_semaphore_post(osal_semaphore_t se
   }
   else
   {
-    BaseType_t xHigherPriorityTaskWoken;
+    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
     BaseType_t res = xSemaphoreGiveFromISR(sem_hdl, &xHigherPriorityTaskWoken);
 
 #if CFG_TUSB_MCU == OPT_MCU_ESP32S2 || CFG_TUSB_MCU == OPT_MCU_ESP32S3
@@ -189,7 +189,7 @@ TU_ATTR_ALWAYS_INLINE static inline bool osal_queue_send(osal_queue_t qhdl, void
   }
   else
   {
-    BaseType_t xHigherPriorityTaskWoken;
+    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
     BaseType_t res = xQueueSendToBackFromISR(qhdl, data, &xHigherPriorityTaskWoken);
 
 #if CFG_TUSB_MCU == OPT_MCU_ESP32S2 || CFG_TUSB_MCU == OPT_MCU_ESP32S3
diff --git a/src/osal/osal_none.h b/src/osal/osal_none.h
index 9c80e4548..1ad130557 100644
--- a/src/osal/osal_none.h
+++ b/src/osal/osal_none.h
@@ -82,6 +82,10 @@ TU_ATTR_ALWAYS_INLINE static inline void osal_semaphore_reset(osal_semaphore_t s
 typedef osal_semaphore_def_t osal_mutex_def_t;
 typedef osal_semaphore_t osal_mutex_t;
 
+#if OSAL_MUTEX_REQUIRED
+// Note: multiple cores MCUs usually do provide IPC API for mutex
+// or we can use std atomic function
+
 TU_ATTR_ALWAYS_INLINE static inline osal_mutex_t osal_mutex_create(osal_mutex_def_t* mdef)
 {
   mdef->count = 1;
@@ -98,6 +102,14 @@ TU_ATTR_ALWAYS_INLINE static inline bool osal_mutex_unlock(osal_mutex_t mutex_hd
   return osal_semaphore_post(mutex_hdl, false);
 }
 
+#else
+
+#define osal_mutex_create(_mdef)          (NULL)
+#define osal_mutex_lock(_mutex_hdl, _ms)  (true)
+#define osal_mutex_unlock(_mutex_hdl)     (true)
+
+#endif
+
 //--------------------------------------------------------------------+
 // QUEUE API
 //--------------------------------------------------------------------+
diff --git a/src/osal/osal_rtthread.h b/src/osal/osal_rtthread.h
index f8452bfb2..18eb9c693 100644
--- a/src/osal/osal_rtthread.h
+++ b/src/osal/osal_rtthread.h
@@ -63,7 +63,7 @@ TU_ATTR_ALWAYS_INLINE static inline bool osal_semaphore_wait(osal_semaphore_t se
 }
 
 TU_ATTR_ALWAYS_INLINE static inline void osal_semaphore_reset(osal_semaphore_t const sem_hdl) {
-    // TODO: implement
+    rt_sem_control(sem_hdl, RT_IPC_CMD_RESET, 0);
 }
 
 //--------------------------------------------------------------------+