diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index 23e34213..ae1eef8a 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -209,10 +209,11 @@ bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
   return true;
 }
 
-void cdch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
+bool cdch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
 {
   (void) ep_addr;
   tuh_cdc_xfer_isr( dev_addr, event, 0, xferred_bytes );
+  return true;
 }
 
 void cdch_close(uint8_t dev_addr)
diff --git a/src/class/cdc/cdc_host.h b/src/class/cdc/cdc_host.h
index 0e2820fe..f28a0a71 100644
--- a/src/class/cdc/cdc_host.h
+++ b/src/class/cdc/cdc_host.h
@@ -113,7 +113,7 @@ void tuh_cdc_xfer_isr(uint8_t dev_addr, xfer_result_t event, cdc_pipeid_t pipe_i
 //--------------------------------------------------------------------+
 void cdch_init(void);
 bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf_desc, uint16_t *p_length);
-void cdch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
+bool cdch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
 void cdch_close(uint8_t dev_addr);
 
 #ifdef __cplusplus
diff --git a/src/class/hid/hid_host.c b/src/class/hid/hid_host.c
index 5ea8cc7e..6002ead3 100644
--- a/src/class/hid/hid_host.c
+++ b/src/class/hid/hid_host.c
@@ -233,7 +233,7 @@ bool hidh_open_subtask(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t c
   return true;
 }
 
-void hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
+bool hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
 {
   (void) xferred_bytes; // TODO may need to use this para later
 
@@ -241,7 +241,7 @@ void hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32
   if ( ep_addr == keyboardh_data[dev_addr-1].ep_in )
   {
     tuh_hid_keyboard_isr(dev_addr, event);
-    return;
+    return true;
   }
 #endif
 
@@ -249,13 +249,15 @@ void hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32
   if ( ep_addr == mouseh_data[dev_addr-1].ep_in )
   {
     tuh_hid_mouse_isr(dev_addr, event);
-    return;
+    return true;
   }
 #endif
 
 #if CFG_TUSB_HOST_HID_GENERIC
 
 #endif
+
+  return true;
 }
 
 void hidh_close(uint8_t dev_addr)
diff --git a/src/class/hid/hid_host.h b/src/class/hid/hid_host.h
index 54542de5..324dad20 100644
--- a/src/class/hid/hid_host.h
+++ b/src/class/hid/hid_host.h
@@ -197,7 +197,7 @@ void tuh_hid_generic_isr(uint8_t dev_addr, xfer_result_t event);
 //--------------------------------------------------------------------+
 void hidh_init(void);
 bool hidh_open_subtask(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *p_interface_desc, uint16_t *p_length);
-void hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
+bool hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
 void hidh_close(uint8_t dev_addr);
 
 #ifdef __cplusplus
diff --git a/src/class/msc/msc_host.c b/src/class/msc/msc_host.c
index b129d538..f47bbd16 100644
--- a/src/class/msc/msc_host.c
+++ b/src/class/msc/msc_host.c
@@ -336,6 +336,7 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
 
   enum { SCSI_XFER_TIMEOUT = 2000 };
   //------------- SCSI Inquiry -------------//
+  TU_LOG2("SCSI Inquiry\r\n");
   tusbh_msc_inquiry(dev_addr, 0, msch_buffer);
   TU_ASSERT( osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT) );
 
@@ -343,6 +344,7 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
   memcpy(p_msc->product_id, ((scsi_inquiry_resp_t*) msch_buffer)->product_id, 16);
 
   //------------- SCSI Read Capacity 10 -------------//
+  TU_LOG2("SCSI Read Capacity 10\r\n");
   tusbh_msc_read_capacity10(dev_addr, 0, msch_buffer);
   TU_ASSERT( osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT));
 
@@ -383,7 +385,7 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
   return true;
 }
 
-void msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
+bool msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
 {
   msch_interface_t* p_msc = &msch_data[dev_addr-1];
   if ( ep_addr == p_msc->ep_in )
@@ -396,6 +398,8 @@ void msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32
       osal_semaphore_post(msch_sem_hdl, true);
     }
   }
+
+  return true;
 }
 
 void msch_close(uint8_t dev_addr)
diff --git a/src/class/msc/msc_host.h b/src/class/msc/msc_host.h
index 3eb45e6f..a3213421 100644
--- a/src/class/msc/msc_host.h
+++ b/src/class/msc/msc_host.h
@@ -193,7 +193,7 @@ typedef struct
 
 void msch_init(void);
 bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf_desc, uint16_t *p_length);
-void msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
+bool msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
 void msch_close(uint8_t dev_addr);
 
 #ifdef __cplusplus
diff --git a/src/host/hub.c b/src/host/hub.c
index abec20d0..ed96713e 100644
--- a/src/host/hub.c
+++ b/src/host/hub.c
@@ -175,7 +175,7 @@ bool hub_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf
 
 // is the response of interrupt endpoint polling
 #include "usbh_hcd.h" // FIXME remove
-void hub_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
+bool hub_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
 {
   (void) xferred_bytes; // TODO can be more than 1 for hub with lots of ports
   (void) ep_addr;
@@ -227,6 +227,8 @@ void hub_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32
     // TODO [HUB] check if hub is still plugged before polling status endpoint since failed usually mean hub unplugged
 //    TU_ASSERT ( hub_status_pipe_queue(dev_addr) );
   }
+
+  return true;
 }
 
 void hub_close(uint8_t dev_addr)
diff --git a/src/host/hub.h b/src/host/hub.h
index 71dd39b8..f00f13de 100644
--- a/src/host/hub.h
+++ b/src/host/hub.h
@@ -182,7 +182,7 @@ bool hub_status_pipe_queue(uint8_t dev_addr);
 //--------------------------------------------------------------------+
 void hub_init(void);
 bool hub_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf_desc, uint16_t *p_length);
-void hub_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
+bool hub_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes);
 void hub_close(uint8_t dev_addr);
 
 #ifdef __cplusplus
diff --git a/src/host/usbh.c b/src/host/usbh.c
index da35340c..a7f6397c 100644
--- a/src/host/usbh.c
+++ b/src/host/usbh.c
@@ -48,7 +48,7 @@
   #define DRIVER_NAME(_name)
 #endif
 
-static host_class_driver_t const usbh_class_drivers[] =
+static usbh_class_driver_t const usbh_class_drivers[] =
 {
   #if CFG_TUH_CDC
     {
@@ -442,7 +442,7 @@ bool enum_task(hcd_event_t* event)
   dev0->state    = TUSB_DEVICE_STATE_UNPLUG;
 
   //------------- connected/disconnected directly with roothub -------------//
-  if ( dev0->hub_addr == 0)
+  if (dev0->hub_addr == 0)
   {
     // wait until device is stable. Increase this if the first 8 bytes is failed to get
     osal_task_delay(POWER_STABLE_DELAY);
diff --git a/src/host/usbh.h b/src/host/usbh.h
index 10e0c21b..91afb90a 100644
--- a/src/host/usbh.h
+++ b/src/host/usbh.h
@@ -60,9 +60,9 @@ typedef struct {
 
   void (* const init) (void);
   bool (* const open)(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const * itf_desc, uint16_t* outlen);
-  void (* const xfer_cb) (uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t len);
+  bool (* const xfer_cb) (uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
   void (* const close) (uint8_t);
-} host_class_driver_t;
+} usbh_class_driver_t;
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
@@ -107,6 +107,9 @@ bool usbh_edpt_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_endpoint_t const
 
 bool usbh_edpt_xfer(uint8_t dev_addr, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes);
 
+
+bool tuh_control_xfer (uint8_t dev_addr, tusb_control_request_t const* request, uint8_t* buffer, uint16_t buflen);
+
 #ifdef __cplusplus
  }
 #endif