diff --git a/tests/test/host/test_usbh.c b/tests/test/host/test_usbh.c
index e8b38eda6..315fdee58 100644
--- a/tests/test/host/test_usbh.c
+++ b/tests/test/host/test_usbh.c
@@ -87,6 +87,12 @@ void test_usbh_init_hcd_failed(void)
 void test_usbh_init_enum_task_create_failed(void)
 {
   hcd_init_ExpectAndReturn(TUSB_ERROR_NONE);
+  for (uint8_t i=0; i<TUSB_CFG_HOST_DEVICE_MAX; i++)
+  {
+    osal_semaphore_handle_t sem_hdl_dummy = 0x2233;
+    osal_semaphore_create_IgnoreAndReturn(sem_hdl_dummy);
+  }
+
   osal_task_create_IgnoreAndReturn(TUSB_ERROR_OSAL_TASK_FAILED);
   TEST_ASSERT_EQUAL(TUSB_ERROR_OSAL_TASK_FAILED, usbh_init());
 }
@@ -94,6 +100,13 @@ void test_usbh_init_enum_task_create_failed(void)
 void test_usbh_init_enum_queue_create_failed(void)
 {
   hcd_init_ExpectAndReturn(TUSB_ERROR_NONE);
+  for (uint8_t i=0; i<TUSB_CFG_HOST_DEVICE_MAX; i++)
+  {
+    osal_semaphore_handle_t sem_hdl_dummy = 0x2233;
+    osal_semaphore_create_IgnoreAndReturn(sem_hdl_dummy);
+  }
+
+
   osal_task_create_IgnoreAndReturn(TUSB_ERROR_NONE);
   osal_queue_create_IgnoreAndReturn(NULL);
   TEST_ASSERT_EQUAL(TUSB_ERROR_OSAL_QUEUE_FAILED, usbh_init());
@@ -118,12 +131,21 @@ void class_init_expect(void)
 
 void test_usbh_init_ok(void)
 {
-  osal_queue_handle_t dummy;
+  osal_queue_handle_t dummy = 0x1122;
+
 
   usbh_device_info_t device_info_zero[TUSB_CFG_HOST_DEVICE_MAX+1];
   memclr_(device_info_zero, sizeof(usbh_device_info_t)*(TUSB_CFG_HOST_DEVICE_MAX+1));
 
   hcd_init_ExpectAndReturn(TUSB_ERROR_NONE);
+
+  for (uint8_t i=0; i<TUSB_CFG_HOST_DEVICE_MAX; i++)
+  {
+    osal_semaphore_handle_t sem_hdl_dummy = 0x2233;
+    osal_semaphore_create_IgnoreAndReturn(sem_hdl_dummy);
+    device_info_zero[i].sem_hdl = sem_hdl_dummy;
+  }
+
   osal_task_create_IgnoreAndReturn(TUSB_ERROR_NONE);
   osal_queue_create_IgnoreAndReturn(dummy);
 
diff --git a/tinyusb/host/ehci/ehci.c b/tinyusb/host/ehci/ehci.c
index 46ea67bf1..faabb4a55 100644
--- a/tinyusb/host/ehci/ehci.c
+++ b/tinyusb/host/ehci/ehci.c
@@ -340,7 +340,6 @@ static inline ehci_qtd_t* get_control_qtds(uint8_t dev_addr) ATTR_ALWAYS_INLINE
 //--------------------------------------------------------------------+
 // CONTROL PIPE API
 //--------------------------------------------------------------------+
-// TODO subject to pure function
 static void init_qtd(ehci_qtd_t* p_qtd, uint32_t data_ptr, uint16_t total_bytes)
 {
   memclr_(p_qtd, sizeof(ehci_qtd_t));
@@ -537,7 +536,6 @@ static inline ehci_qtd_t* get_control_qtds(uint8_t dev_addr)
 
 }
 
-// TODO subject to pure function
 static void init_qhd(ehci_qhd_t *p_qhd, uint8_t dev_addr, uint16_t max_packet_size, uint8_t endpoint_addr, uint8_t xfer_type)
 {
   memclr_(p_qhd, sizeof(ehci_qhd_t));
diff --git a/tinyusb/host/usbh.c b/tinyusb/host/usbh.c
index c84abbc5d..ad4bf3b2a 100644
--- a/tinyusb/host/usbh.c
+++ b/tinyusb/host/usbh.c
@@ -103,6 +103,13 @@ tusb_error_t usbh_init(void)
 
   ASSERT_STATUS( hcd_init() );
 
+  //------------- Semaphore for Control Pipe -------------//
+  for(uint8_t i=0; i<TUSB_CFG_HOST_DEVICE_MAX; i++)
+  {
+    usbh_device_info_pool[i].sem_hdl = osal_semaphore_create( OSAL_SEM_REF(usbh_device_info_pool[i].semaphore) );
+    ASSERT_PTR(usbh_device_info_pool[i].sem_hdl, TUSB_ERROR_OSAL_SEMAPHORE_FAILED);
+  }
+
   //------------- Enumeration & Reporter Task init -------------//
   ASSERT_STATUS( osal_task_create(&enum_task) );
   enum_queue_hdl = osal_queue_create(&enum_queue);
@@ -118,9 +125,19 @@ tusb_error_t usbh_init(void)
   return TUSB_ERROR_NONE;
 }
 
+// interrupt caused by a TD (with IOC=1) in pipe of class class_code
 void usbh_isr(pipe_handle_t pipe_hdl, uint8_t class_code)
 {
-
+  if (class_code == 0) // Control transfer
+  {
+    // TODO some semaphore posting
+  }else if (usbh_class_drivers[class_code].isr)
+  {
+    usbh_class_drivers[class_code].isr(pipe_hdl);
+  }else
+  {
+    ASSERT(false, (void) 0); // something wrong, no one claims the isr's source
+  }
 }
 
 // function called within a task, requesting os blocking services, subtask input parameter must be static/global variables
diff --git a/tinyusb/host/usbh_hcd.h b/tinyusb/host/usbh_hcd.h
index ab4bef49b..03901050b 100644
--- a/tinyusb/host/usbh_hcd.h
+++ b/tinyusb/host/usbh_hcd.h
@@ -90,20 +90,12 @@ typedef struct { // TODO internal structure, re-order members
   //------------- configuration descriptor info -------------//
   uint8_t interface_count; // bNumInterfaces alias
 
-  uint8_t status; // value from enum tusbh_device_status_
+  uint8_t status;          // value from enum tusbh_device_status_
 
-//  pipe_handle_t pipe_control; NOTE: use device address/handle instead
   tusb_std_request_t control_request;
   OSAL_SEM_DEF(semaphore);
   osal_semaphore_handle_t sem_hdl;
 
-#if 0 // TODO allow configure for vendor/product
-  struct {
-    uint8_t interface_count;
-    uint8_t attributes;
-  } configuration;
-#endif
-
 } usbh_device_info_t;
 
 extern usbh_device_info_t usbh_device_info_pool[TUSB_CFG_HOST_DEVICE_MAX+1]; // including zero-address
diff --git a/tinyusb/osal/osal.h b/tinyusb/osal/osal.h
index b1f67055f..09b9560fb 100644
--- a/tinyusb/osal/osal.h
+++ b/tinyusb/osal/osal.h
@@ -147,6 +147,9 @@ typedef void* osal_semaphore_handle_t;
 #define OSAL_SEM_DEF(name)\
   osal_semaphore_t name
 
+#define OSAL_SEM_REF(name)\
+  &name
+
 osal_semaphore_handle_t osal_semaphore_create(osal_semaphore_t * const sem);
 void osal_semaphore_wait(osal_semaphore_handle_t const sem_hdl, uint32_t msec, tusb_error_t *p_error);
 tusb_error_t osal_semaphore_post(osal_semaphore_handle_t const sem_hdl);
diff --git a/tinyusb/osal/osal_none.h b/tinyusb/osal/osal_none.h
index da42a969a..82bef38b1 100644
--- a/tinyusb/osal/osal_none.h
+++ b/tinyusb/osal/osal_none.h
@@ -150,6 +150,7 @@ static inline uint32_t osal_tick_get(void)
 #define SUBTASK_ASSERT_STATUS_WITH_HANDLER(...)  TASK_ASSERT_STATUS_WITH_HANDLER(__VA_ARGS__)
 #define SUBTASK_ASSERT(...)                      TASK_ASSERT(__VA_ARGS__)
 #define SUBTASK_ASSERT_WITH_HANDLER(...)         TASK_ASSERT_WITH_HANDLER(__VA_ARGS__)
+
 //--------------------------------------------------------------------+
 // Semaphore API
 //--------------------------------------------------------------------+
@@ -177,6 +178,12 @@ static inline  tusb_error_t osal_semaphore_post(osal_semaphore_handle_t const se
   return TUSB_ERROR_NONE;
 }
 
+static inline void osal_sempahore_reset(osal_semaphore_handle_t const sem_hdl) ATTR_ALWAYS_INLINE;
+static inline void osal_sempahore_reset(osal_semaphore_handle_t const sem_hdl)
+{
+  (*sem_hdl) = 0;
+}
+
 #define osal_semaphore_wait(sem_hdl, msec, p_error) \
   do {\
     timeout = osal_tick_get();\
@@ -242,6 +249,12 @@ static inline tusb_error_t osal_queue_send(osal_queue_handle_t const queue_hdl,
   return TUSB_ERROR_NONE;
 }
 
+static inline void osal_queue_flush(osal_queue_handle_t const queue_hdl) ATTR_ALWAYS_INLINE;
+static inline void osal_queue_flush(osal_queue_handle_t const queue_hdl)
+{
+  queue_hdl->count = queue_hdl->rd_idx = queue_hdl->wr_idx = 0;
+}
+
 #define osal_queue_receive(queue_hdl, p_data, msec, p_error) \
   do {\
     timeout = osal_tick_get();\