diff --git a/examples/host/cdc_msc_hid/src/msc_app.c b/examples/host/cdc_msc_hid/src/msc_app.c
index 62bd961c1..53f0e6ac2 100644
--- a/examples/host/cdc_msc_hid/src/msc_app.c
+++ b/examples/host/cdc_msc_hid/src/msc_app.c
@@ -38,6 +38,7 @@ void tuh_msc_mounted_cb(uint8_t dev_addr)
   printf("A MassStorage device is mounted\r\n");
 
   //------------- Disk Information -------------//
+#if 0
   // SCSI VendorID[8] & ProductID[16] from Inquiry Command
   uint8_t const* p_vendor  = tuh_msc_get_vendor_name(dev_addr);
   uint8_t const* p_product = tuh_msc_get_product_name(dev_addr);
@@ -47,6 +48,7 @@ void tuh_msc_mounted_cb(uint8_t dev_addr)
   putchar(' ');
   for(uint8_t i=0; i<16; i++) putchar(p_product[i]);
   putchar('\n');
+#endif
 
   uint32_t last_lba = 0;
   uint32_t block_size = 0;
@@ -103,12 +105,11 @@ void tuh_msc_unmounted_cb(uint8_t dev_addr)
 //  }
 }
 
-// invoked ISR context
-void tuh_msc_isr(uint8_t dev_addr, xfer_result_t event, uint32_t xferred_bytes)
-{
-  (void) dev_addr;
-  (void) event;
-  (void) xferred_bytes;
-}
+//void tuh_msc_scsi_complete_cb(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+//{
+//  (void) dev_addr;
+//  (void) cbw;
+//  (void) csw;
+//}
 
 #endif
diff --git a/src/class/msc/msc_host.c b/src/class/msc/msc_host.c
index f47bbd163..e8bed989c 100644
--- a/src/class/msc/msc_host.c
+++ b/src/class/msc/msc_host.c
@@ -37,19 +37,41 @@
 //--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
-CFG_TUSB_MEM_SECTION static msch_interface_t msch_data[CFG_TUSB_HOST_DEVICE_MAX];
+enum
+{
+  MSC_STAGE_IDLE = 0,
+  MSC_STAGE_CMD,
+  MSC_STAGE_DATA,
+  MSC_STAGE_STATUS,
+};
 
-//------------- Initalization Data -------------//
-static osal_semaphore_def_t msch_sem_def;
-static osal_semaphore_t msch_sem_hdl;
+typedef struct
+{
+  uint8_t  itf_num;
+  uint8_t  ep_in;
+  uint8_t  ep_out;
+
+  uint8_t  max_lun;
+
+  scsi_read_capacity10_resp_t capacity;
+
+  volatile bool is_initialized;
+  uint8_t vendor_id[8];
+  uint8_t product_id[16];
+
+  uint8_t stage;
+  void*   buffer;
+  tuh_msc_complete_cb_t complete_cb;
+
+  msc_cbw_t cbw;
+  msc_csw_t csw;
+}msch_interface_t;
+
+CFG_TUSB_MEM_SECTION static msch_interface_t msch_data[CFG_TUSB_HOST_DEVICE_MAX];
 
 // buffer used to read scsi information when mounted, largest response data currently is inquiry
 CFG_TUSB_MEM_SECTION TU_ATTR_ALIGNED(4) static uint8_t msch_buffer[sizeof(scsi_inquiry_resp_t)];
 
-//--------------------------------------------------------------------+
-// INTERNAL OBJECT & FUNCTION DECLARATION
-//--------------------------------------------------------------------+
-
 //--------------------------------------------------------------------+
 // PUBLIC API
 //--------------------------------------------------------------------+
@@ -65,25 +87,17 @@ bool tuh_msc_is_busy(uint8_t dev_addr)
           hcd_edpt_busy(dev_addr, msch_data[dev_addr-1].ep_in);
 }
 
-uint8_t const* tuh_msc_get_vendor_name(uint8_t dev_addr)
+bool tuh_msc_get_capacity(uint8_t dev_addr, uint32_t* p_last_lba, uint32_t* p_block_size)
 {
-  return msch_data[dev_addr-1].is_initialized ? msch_data[dev_addr-1].vendor_id : NULL;
-}
+  msch_interface_t* p_msc = &msch_data[dev_addr-1];
 
-uint8_t const* tuh_msc_get_product_name(uint8_t dev_addr)
-{
-  return msch_data[dev_addr-1].is_initialized ? msch_data[dev_addr-1].product_id : NULL;
-}
+  if ( !p_msc->is_initialized ) return false;
+  TU_ASSERT(p_last_lba != NULL && p_block_size != NULL);
 
-tusb_error_t tuh_msc_get_capacity(uint8_t dev_addr, uint32_t* p_last_lba, uint32_t* p_block_size)
-{
-  if ( !msch_data[dev_addr-1].is_initialized )   return TUSB_ERROR_MSCH_DEVICE_NOT_MOUNTED;
-  TU_ASSERT(p_last_lba != NULL && p_block_size != NULL, TUSB_ERROR_INVALID_PARA);
+  (*p_last_lba)   = p_msc->capacity.last_lba;
+  (*p_block_size) = p_msc->capacity.block_size;
 
-  (*p_last_lba)   = msch_data[dev_addr-1].last_lba;
-  (*p_block_size) = (uint32_t) msch_data[dev_addr-1].block_size;
-
-  return TUSB_ERROR_NONE;
+  return true;
 }
 
 //--------------------------------------------------------------------+
@@ -92,30 +106,27 @@ tusb_error_t tuh_msc_get_capacity(uint8_t dev_addr, uint32_t* p_last_lba, uint32
 static inline void msc_cbw_add_signature(msc_cbw_t *p_cbw, uint8_t lun)
 {
   p_cbw->signature  = MSC_CBW_SIGNATURE;
-  p_cbw->tag        = 0xCAFECAFE;
+  p_cbw->tag        = 0x54555342; // TUSB
   p_cbw->lun        = lun;
 }
 
-static tusb_error_t msch_command_xfer(uint8_t dev_addr, msch_interface_t * p_msch, void* p_buffer)
+bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb)
 {
-  if ( NULL != p_buffer)
-  { // there is data phase
-    if (p_msch->cbw.dir & TUSB_DIR_IN_MASK)
-    {
-      TU_ASSERT( hcd_pipe_xfer(dev_addr, p_msch->ep_out, (uint8_t*) &p_msch->cbw, sizeof(msc_cbw_t), false), TUSB_ERROR_FAILED );
-      TU_ASSERT( hcd_pipe_queue_xfer(dev_addr, p_msch->ep_in , p_buffer, p_msch->cbw.total_bytes), TUSB_ERROR_FAILED );
-    }else
-    {
-      TU_ASSERT( hcd_pipe_queue_xfer(dev_addr, p_msch->ep_out, (uint8_t*) &p_msch->cbw, sizeof(msc_cbw_t)), TUSB_ERROR_FAILED );
-      TU_ASSERT( hcd_pipe_xfer(dev_addr, p_msch->ep_out , p_buffer, p_msch->cbw.total_bytes, false), TUSB_ERROR_FAILED );
-    }
-  }
+  msch_interface_t* p_msc = &msch_data[dev_addr-1];
 
-  TU_ASSERT( hcd_pipe_xfer(dev_addr, p_msch->ep_in , (uint8_t*) &p_msch->csw, sizeof(msc_csw_t), true), TUSB_ERROR_FAILED);
+  // TODO claim endpoint
 
-  return TUSB_ERROR_NONE;
+  p_msc->cbw = *cbw;
+  p_msc->stage = MSC_STAGE_CMD;
+  p_msc->buffer = data;
+  p_msc->complete_cb = complete_cb;
+
+  TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_out, (uint8_t*) &p_msc->cbw, sizeof(msc_cbw_t)));
+
+  return true;
 }
 
+#if 0
 tusb_error_t tusbh_msc_inquiry(uint8_t dev_addr, uint8_t lun, uint8_t *p_data)
 {
   msch_interface_t* p_msch = &msch_data[dev_addr-1];
@@ -127,7 +138,7 @@ tusb_error_t tusbh_msc_inquiry(uint8_t dev_addr, uint8_t lun, uint8_t *p_data)
   p_msch->cbw.cmd_len    = sizeof(scsi_inquiry_t);
 
   //------------- SCSI command -------------//
-  scsi_inquiry_t cmd_inquiry =
+  scsi_inquiry_t const cmd_inquiry =
   {
       .cmd_code     = SCSI_CMD_INQUIRY,
       .alloc_length = sizeof(scsi_inquiry_resp_t)
@@ -135,88 +146,51 @@ tusb_error_t tusbh_msc_inquiry(uint8_t dev_addr, uint8_t lun, uint8_t *p_data)
 
   memcpy(p_msch->cbw.command, &cmd_inquiry, p_msch->cbw.cmd_len);
 
-  TU_ASSERT_ERR ( msch_command_xfer(dev_addr, p_msch, p_data) );
+  TU_ASSERT_ERR ( send_cbw(dev_addr, p_msch, p_data) );
 
   return TUSB_ERROR_NONE;
 }
+#endif
 
-tusb_error_t tusbh_msc_read_capacity10(uint8_t dev_addr, uint8_t lun, uint8_t *p_data)
+bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun,  tuh_msc_complete_cb_t complete_cb)
 {
-  msch_interface_t* p_msch = &msch_data[dev_addr-1];
+  msc_cbw_t cbw = { 0 };
+  msc_cbw_add_signature(&cbw, lun);
 
-  //------------- Command Block Wrapper -------------//
-  msc_cbw_add_signature(&p_msch->cbw, lun);
-  p_msch->cbw.total_bytes = sizeof(scsi_read_capacity10_resp_t);
-  p_msch->cbw.dir        = TUSB_DIR_IN_MASK;
-  p_msch->cbw.cmd_len    = sizeof(scsi_read_capacity10_t);
+  cbw.total_bytes = 0; // Number of bytes
+  cbw.dir        = TUSB_DIR_OUT;
+  cbw.cmd_len    = sizeof(scsi_test_unit_ready_t);
+  cbw.command[0] = SCSI_CMD_TEST_UNIT_READY;
+  cbw.command[1] = lun; // according to wiki TODO need verification
 
-  //------------- SCSI command -------------//
-  scsi_read_capacity10_t cmd_read_capacity10 =
+  TU_ASSERT(tuh_msc_scsi_command(dev_addr, &cbw, NULL, complete_cb));
+
+  return true;
+}
+
+bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *resposne, tuh_msc_complete_cb_t complete_cb)
+{
+  msc_cbw_t cbw = { 0 };
+  msc_cbw_add_signature(&cbw, lun);
+
+  cbw.total_bytes = 18; // TODO sense response
+  cbw.dir        = TUSB_DIR_IN_MASK;
+  cbw.cmd_len    = sizeof(scsi_request_sense_t);
+
+  scsi_request_sense_t const cmd_request_sense =
   {
-      .cmd_code                 = SCSI_CMD_READ_CAPACITY_10,
-      .lba                      = 0,
-      .partial_medium_indicator = 0
+    .cmd_code     = SCSI_CMD_REQUEST_SENSE,
+    .alloc_length = 18
   };
 
-  memcpy(p_msch->cbw.command, &cmd_read_capacity10, p_msch->cbw.cmd_len);
+  memcpy(cbw.command, &cmd_request_sense, cbw.cmd_len);
 
-  TU_ASSERT_ERR ( msch_command_xfer(dev_addr, p_msch, p_data) );
+  TU_ASSERT(tuh_msc_scsi_command(dev_addr, &cbw, resposne, complete_cb));
 
-  return TUSB_ERROR_NONE;
-}
-
-tusb_error_t tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, uint8_t *p_data)
-{
-  (void) lun; // TODO [MSCH] multiple lun support
-
-  msch_interface_t* p_msch = &msch_data[dev_addr-1];
-
-  //------------- Command Block Wrapper -------------//
-  p_msch->cbw.total_bytes = 18;
-  p_msch->cbw.dir        = TUSB_DIR_IN_MASK;
-  p_msch->cbw.cmd_len    = sizeof(scsi_request_sense_t);
-
-  //------------- SCSI command -------------//
-  scsi_request_sense_t cmd_request_sense =
-  {
-      .cmd_code     = SCSI_CMD_REQUEST_SENSE,
-      .alloc_length = 18
-  };
-
-  memcpy(p_msch->cbw.command, &cmd_request_sense, p_msch->cbw.cmd_len);
-
-  TU_ASSERT_ERR ( msch_command_xfer(dev_addr, p_msch, p_data) );
-
-  return TUSB_ERROR_NONE;
-}
-
-tusb_error_t tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun,  msc_csw_t * p_csw)
-{
-  msch_interface_t* p_msch = &msch_data[dev_addr-1];
-
-  //------------- Command Block Wrapper -------------//
-  msc_cbw_add_signature(&p_msch->cbw, lun);
-
-  p_msch->cbw.total_bytes = 0; // Number of bytes
-  p_msch->cbw.dir        = TUSB_DIR_OUT;
-  p_msch->cbw.cmd_len    = sizeof(scsi_test_unit_ready_t);
-
-  //------------- SCSI command -------------//
-  scsi_test_unit_ready_t cmd_test_unit_ready =
-  {
-      .cmd_code = SCSI_CMD_TEST_UNIT_READY,
-      .lun      = lun // according to wiki
-  };
-
-  memcpy(p_msch->cbw.command, &cmd_test_unit_ready, p_msch->cbw.cmd_len);
-
-  // TODO MSCH refractor test uinit ready
-  TU_ASSERT( hcd_pipe_xfer(dev_addr, p_msch->ep_out, (uint8_t*) &p_msch->cbw, sizeof(msc_cbw_t), false), TUSB_ERROR_FAILED );
-  TU_ASSERT( hcd_pipe_xfer(dev_addr, p_msch->ep_in , (uint8_t*) p_csw, sizeof(msc_csw_t), true), TUSB_ERROR_FAILED );
-
-  return TUSB_ERROR_NONE;
+  return true;
 }
 
+#if 0
 tusb_error_t  tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * p_buffer, uint32_t lba, uint16_t block_count)
 {
   msch_interface_t* p_msch = &msch_data[dev_addr-1];
@@ -229,7 +203,7 @@ tusb_error_t  tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * p_buffer, uin
   p_msch->cbw.cmd_len    = sizeof(scsi_read10_t);
 
   //------------- SCSI command -------------//
-  scsi_read10_t cmd_read10 =
+  scsi_read10_t cmd_read10 =msch_sem_hdl
   {
       .cmd_code    = SCSI_CMD_READ_10,
       .lba         = tu_htonl(lba),
@@ -238,7 +212,7 @@ tusb_error_t  tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * p_buffer, uin
 
   memcpy(p_msch->cbw.command, &cmd_read10, p_msch->cbw.cmd_len);
 
-  TU_ASSERT_ERR ( msch_command_xfer(dev_addr, p_msch, p_buffer));
+  TU_ASSERT_ERR ( send_cbw(dev_addr, p_msch, p_buffer));
 
   return TUSB_ERROR_NONE;
 }
@@ -264,10 +238,11 @@ tusb_error_t tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * p_buffe
 
   memcpy(p_msch->cbw.command, &cmd_write10, p_msch->cbw.cmd_len);
 
-  TU_ASSERT_ERR ( msch_command_xfer(dev_addr, p_msch, (void*) p_buffer));
+  TU_ASSERT_ERR ( send_cbw(dev_addr, p_msch, (void*) p_buffer));
 
   return TUSB_ERROR_NONE;
 }
+#endif
 
 //--------------------------------------------------------------------+
 // CLASS-USBH API (don't require to verify parameters)
@@ -275,9 +250,75 @@ tusb_error_t tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * p_buffe
 void msch_init(void)
 {
   tu_memclr(msch_data, sizeof(msch_interface_t)*CFG_TUSB_HOST_DEVICE_MAX);
-  msch_sem_hdl = osal_semaphore_create(&msch_sem_def);
 }
 
+
+void msch_close(uint8_t dev_addr)
+{
+  tu_memclr(&msch_data[dev_addr-1], sizeof(msch_interface_t));
+  tuh_msc_unmounted_cb(dev_addr); // invoke Application Callback
+}
+
+static bool get_csw(uint8_t dev_addr, msch_interface_t * p_msc)
+{
+  p_msc->stage = MSC_STAGE_STATUS;
+  TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_in, (uint8_t*) &p_msc->csw, sizeof(msc_csw_t)));
+  return true;
+}
+
+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];
+  msc_cbw_t const * cbw = &p_msc->cbw;
+  msc_csw_t       * csw = &p_msc->csw;
+
+  switch (p_msc->stage)
+  {
+    case MSC_STAGE_CMD:
+      // Must be Command Block
+      TU_ASSERT(ep_addr == p_msc->ep_out &&  event == XFER_RESULT_SUCCESS && xferred_bytes == sizeof(msc_cbw_t));
+
+      if ( cbw->total_bytes && p_msc->buffer )
+      {
+        // Data stage if any
+        p_msc->stage = MSC_STAGE_DATA;
+
+        uint8_t const ep_data = (cbw->dir & TUSB_DIR_IN_MASK) ? p_msc->ep_in : p_msc->ep_out;
+        TU_ASSERT(usbh_edpt_xfer(dev_addr, ep_data, p_msc->buffer, cbw->total_bytes));
+      }else
+      {
+        // Status stage
+        get_csw(dev_addr, p_msc);
+      }
+    break;
+
+    case MSC_STAGE_DATA:
+      get_csw(dev_addr, p_msc);
+    break;
+
+    case MSC_STAGE_STATUS:
+      // SCSI op is complete
+      p_msc->stage = MSC_STAGE_IDLE;
+
+      if (p_msc->complete_cb) p_msc->complete_cb(dev_addr, cbw, csw);
+    break;
+
+    // unknown state
+    default: break;
+  }
+
+  return true;
+}
+
+//--------------------------------------------------------------------+
+// MSC Enumeration
+//--------------------------------------------------------------------+
+
+static bool open_get_maxlun_complete (uint8_t dev_addr, tusb_control_request_t const * request, xfer_result_t result);
+static bool open_test_unit_ready_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+static bool open_request_sense_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+static bool open_read_capacity10_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+
 bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf_desc, uint16_t *p_length)
 {
   TU_VERIFY (MSC_SUBCLASS_SCSI == itf_desc->bInterfaceSubClass &&
@@ -311,30 +352,52 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
 
   //------------- Get Max Lun -------------//
   TU_LOG2("MSC Get Max Lun\r\n");
-  tusb_control_request_t request = {
-        .bmRequestType_bit = { .recipient = TUSB_REQ_RCPT_INTERFACE, .type = TUSB_REQ_TYPE_CLASS, .direction = TUSB_DIR_IN },
-        .bRequest = MSC_REQ_GET_MAX_LUN,
-        .wValue = 0,
-        .wIndex = p_msc->itf_num,
-        .wLength = 1
+  tusb_control_request_t request =
+  {
+    .bmRequestType_bit =
+    {
+      .recipient = TUSB_REQ_RCPT_INTERFACE,
+      .type      = TUSB_REQ_TYPE_CLASS,
+      .direction = TUSB_DIR_IN
+    },
+    .bRequest = MSC_REQ_GET_MAX_LUN,
+    .wValue   = 0,
+    .wIndex   = p_msc->itf_num,
+    .wLength  = 1
   };
-  // TODO STALL means zero
-  TU_ASSERT( usbh_control_xfer( dev_addr, &request, msch_buffer ) );
-  p_msc->max_lun = msch_buffer[0];
+  TU_ASSERT(tuh_control_xfer(dev_addr, &request, msch_buffer, open_get_maxlun_complete));
 
-#if 0
-  //------------- Reset -------------//
-  request = (tusb_control_request_t) {
-        .bmRequestType_bit = { .recipient = TUSB_REQ_RCPT_INTERFACE, .type = TUSB_REQ_TYPE_CLASS, .direction = TUSB_DIR_OUT },
-        .bRequest = MSC_REQ_RESET,
-        .wValue = 0,
-        .wIndex = p_msc->itf_num,
-        .wLength = 0
+  return true;
+}
+
+static bool open_get_maxlun_complete (uint8_t dev_addr, tusb_control_request_t const * request, xfer_result_t result)
+{
+  (void) request;
+
+  msch_interface_t* p_msc = &msch_data[dev_addr-1];
+
+  // STALL means zero
+  p_msc->max_lun = (XFER_RESULT_SUCCESS == result) ? msch_buffer[0] : 0;
+
+  // MSCU Reset
+#if 0 // not really needed
+  tusb_control_request_t const new_request =
+  {
+    .bmRequestType_bit =
+    {
+      .recipient = TUSB_REQ_RCPT_INTERFACE,
+      .type      = TUSB_REQ_TYPE_CLASS,
+      .direction = TUSB_DIR_OUT
+    },
+    .bRequest = MSC_REQ_RESET,
+    .wValue   = 0,
+    .wIndex   = p_msc->itf_num,
+    .wLength  = 0
   };
-  TU_ASSERT( usbh_control_xfer( dev_addr, &request, NULL ) );
+  TU_ASSERT( usbh_control_xfer( dev_addr, &new_request, NULL ) );
 #endif
 
-  enum { SCSI_XFER_TIMEOUT = 2000 };
+#if 0
   //------------- SCSI Inquiry -------------//
   TU_LOG2("SCSI Inquiry\r\n");
   tusbh_msc_inquiry(dev_addr, 0, msch_buffer);
@@ -342,77 +405,63 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
 
   memcpy(p_msc->vendor_id , ((scsi_inquiry_resp_t*) msch_buffer)->vendor_id , 8);
   memcpy(p_msc->product_id, ((scsi_inquiry_resp_t*) msch_buffer)->product_id, 16);
+#endif
 
-  //------------- 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));
+  // TODO multiple LUN support
+  TU_LOG2("SCSI Test Unit Ready\r\n");
+  tuh_msc_test_unit_ready(dev_addr, 0, open_test_unit_ready_complete);
 
-  // NOTE: my toshiba thumb-drive stall the first Read Capacity and require the sequence
-  // Read Capacity --> Stalled --> Clear Stall --> Request Sense --> Read Capacity (2) to work
-  if ( hcd_edpt_stalled(dev_addr, p_msc->ep_in) )
+  return true;
+}
+
+static bool open_test_unit_ready_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+{
+  if (csw->status == 0)
   {
-    // clear stall TODO abstract clear stall function
-    request = (tusb_control_request_t) {
-      .bmRequestType_bit = { .recipient = TUSB_REQ_RCPT_ENDPOINT, .type = TUSB_REQ_TYPE_STANDARD, .direction = TUSB_DIR_OUT },
-          .bRequest = TUSB_REQ_CLEAR_FEATURE,
-          .wValue = 0,
-          .wIndex = p_msc->ep_in,
-          .wLength = 0
-    };
+    TU_LOG2("SCSI Read Capacity 10\r\n");
 
-    TU_ASSERT(usbh_control_xfer( dev_addr, &request, NULL ));
+    msch_interface_t* p_msc = &msch_data[dev_addr-1];
+    msc_cbw_t new_cbw = { 0 };
 
-    hcd_edpt_clear_stall(dev_addr, p_msc->ep_in);
-    TU_ASSERT( osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT) ); // wait for SCSI status
+    msc_cbw_add_signature(&new_cbw, cbw->lun);
+    new_cbw.total_bytes = sizeof(scsi_read_capacity10_resp_t);
+    new_cbw.dir        = TUSB_DIR_IN_MASK;
+    new_cbw.cmd_len    = sizeof(scsi_read_capacity10_t);
+    new_cbw.command[0] = SCSI_CMD_READ_CAPACITY_10;
 
-    //------------- SCSI Request Sense -------------//
-    (void) tuh_msc_request_sense(dev_addr, 0, msch_buffer);
-    TU_ASSERT(osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT));
-
-    //------------- Re-read SCSI Read Capactity -------------//
-    tusbh_msc_read_capacity10(dev_addr, 0, msch_buffer);
-    TU_ASSERT(osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT));
+    TU_ASSERT(tuh_msc_scsi_command(dev_addr, &new_cbw, &p_msc->capacity, open_read_capacity10_complete));
+  }else
+  {
+    // Note: During enumeration, some device fails Test Unit Ready and require a few retries
+    // with Request Sense to start working !!
+    // TODO limit number of retries
+    TU_ASSERT(tuh_msc_request_sense(dev_addr, cbw->lun, msch_buffer, open_request_sense_complete));
   }
 
-  p_msc->last_lba   = tu_ntohl( ((scsi_read_capacity10_resp_t*)msch_buffer)->last_lba );
-  p_msc->block_size = (uint16_t) tu_ntohl( ((scsi_read_capacity10_resp_t*)msch_buffer)->block_size );
+  return true;
+}
 
-  p_msc->is_initialized = true;
+static bool open_request_sense_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+{
+  TU_ASSERT(tuh_msc_test_unit_ready(dev_addr, cbw->lun, open_test_unit_ready_complete));
+  return true;
+}
 
+static bool open_read_capacity10_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+{
+  TU_ASSERT(csw->status == 0);
+
+  msch_interface_t* p_msc = &msch_data[dev_addr-1];
+
+  // Note: Block size and last LBA are big-endian
+  p_msc->capacity.last_lba = tu_ntohl(p_msc->capacity.last_lba);
+  p_msc->capacity.block_size = tu_ntohl(p_msc->capacity.block_size);
+
+  // Enumeration is complete
+  p_msc->is_initialized = true; // open complete TODO remove
   tuh_msc_mounted_cb(dev_addr);
 
   return true;
 }
 
-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 )
-  {
-    if (p_msc->is_initialized)
-    {
-      tuh_msc_isr(dev_addr, event, xferred_bytes);
-    }else
-    { // still initializing under open subtask
-      osal_semaphore_post(msch_sem_hdl, true);
-    }
-  }
-
-  return true;
-}
-
-void msch_close(uint8_t dev_addr)
-{
-  tu_memclr(&msch_data[dev_addr-1], sizeof(msch_interface_t));
-  osal_semaphore_reset(msch_sem_hdl);
-
-  tuh_msc_unmounted_cb(dev_addr); // invoke Application Callback
-}
-
-//--------------------------------------------------------------------+
-// INTERNAL & HELPER
-//--------------------------------------------------------------------+
-
-
 #endif
diff --git a/src/class/msc/msc_host.h b/src/class/msc/msc_host.h
index a32134215..03231d17f 100644
--- a/src/class/msc/msc_host.h
+++ b/src/class/msc/msc_host.h
@@ -40,6 +40,9 @@
  * \defgroup MSC_Host Host
  *  The interface API includes status checking function, data transferring function and callback functions
  *  @{ */
+
+typedef bool (*tuh_msc_complete_cb_t)(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+
 //--------------------------------------------------------------------+
 // MASS STORAGE Application API
 //--------------------------------------------------------------------+
@@ -60,23 +63,9 @@ bool          tuh_msc_is_mounted(uint8_t dev_addr);
  */
 bool          tuh_msc_is_busy(uint8_t dev_addr);
 
-/** \brief      Get SCSI vendor's name of MassStorage device
- * \param[in]   dev_addr device address
- * \return      pointer to vendor's name or NULL if specified device does not support MassStorage
- * \note        SCSI vendor's name is 8-byte length field in \ref scsi_inquiry_data_t. During enumeration, the stack has already
- *              retrieved (via SCSI INQUIRY) and store this information internally. There is no need for application to re-send SCSI INQUIRY
- *              command or allocate buffer for this.
- */
-uint8_t const* tuh_msc_get_vendor_name(uint8_t dev_addr);
+bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb);
 
-/** \brief      Get SCSI product's name of MassStorage device
- * \param[in]   dev_addr device address
- * \return      pointer to product's name or NULL if specified device does not support MassStorage
- * \note        SCSI product's name is 16-byte length field in \ref scsi_inquiry_data_t. During enumeration, the stack has already
- *              retrieved (via SCSI INQUIRY) and store this information internally. There is no need for application to re-send SCSI INQUIRY
- *              command or allocate buffer for this.
- */
-uint8_t const* tuh_msc_get_product_name(uint8_t dev_addr);
+bool tuh_msc_scsi_inquiry(uint8_t dev_addr, uint8_t lun, void* response, uint32_t len);
 
 /** \brief      Get SCSI Capacity of MassStorage device
  * \param[in]   dev_addr device address
@@ -87,8 +76,10 @@ uint8_t const* tuh_msc_get_product_name(uint8_t dev_addr);
  *              retrieved (via SCSI READ CAPACITY 10) and store this information internally. There is no need for application
  *              to re-send SCSI READ CAPACITY 10 command
  */
-tusb_error_t tuh_msc_get_capacity(uint8_t dev_addr, uint32_t* p_last_lba, uint32_t* p_block_size);
 
+bool tuh_msc_get_capacity(uint8_t dev_addr, uint32_t* p_last_lba, uint32_t* p_block_size);
+
+#if 0
 /** \brief 			Perform SCSI READ 10 command to read data from MassStorage device
  * \param[in]		dev_addr	device address
  * \param[in]		lun       Targeted Logical Unit
@@ -116,29 +107,25 @@ tusb_error_t tuh_msc_read10 (uint8_t dev_addr, uint8_t lun, void * p_buffer, uin
  * \note        This function is non-blocking and returns immediately. The result of USB transfer will be reported by the interface's callback function
  */
 tusb_error_t tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * p_buffer, uint32_t lba, uint16_t block_count);
+#endif
 
 /** \brief 			Perform SCSI REQUEST SENSE command, used to retrieve sense data from MassStorage device
  * \param[in]		dev_addr	device address
  * \param[in]		lun       Targeted Logical Unit
  * \param[in]	  p_data    Buffer to store response's data from device. Must be accessible by USB controller (see \ref CFG_TUSB_MEM_SECTION)
- * \retval      TUSB_ERROR_NONE on success
- * \retval      TUSB_ERROR_INTERFACE_IS_BUSY if the interface is already transferring data with device
- * \retval      TUSB_ERROR_DEVICE_NOT_READY if device is not yet configured (by SET CONFIGURED request)
- * \retval      TUSB_ERROR_INVALID_PARA if input parameters are not correct
- * \note        This function is non-blocking and returns immediately. The result of USB transfer will be reported by the interface's callback function
+ * \note        This function is non-blocking and returns immediately.
+ *              Callback is invoked when command is complete
  */
-tusb_error_t tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, uint8_t *p_data);
+bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *resposne, tuh_msc_complete_cb_t complete_cb);
 
 /** \brief 			Perform SCSI TEST UNIT READY command to test if MassStorage device is ready
  * \param[in]		dev_addr	device address
  * \param[in]		lun       Targeted Logical Unit
- * \retval      TUSB_ERROR_NONE on success
- * \retval      TUSB_ERROR_INTERFACE_IS_BUSY if the interface is already transferring data with device
- * \retval      TUSB_ERROR_DEVICE_NOT_READY if device is not yet configured (by SET CONFIGURED request)
- * \retval      TUSB_ERROR_INVALID_PARA if input parameters are not correct
- * \note        This function is non-blocking and returns immediately. The result of USB transfer will be reported by the interface's callback function
+ * \note        This function is non-blocking and returns immediately.
+ *              Callback is invoked when command is complete
  */
-tusb_error_t tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, msc_csw_t * p_csw); // TODO to be refractor
+bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_t complete_cb);
+
 
 //tusb_error_t  tusbh_msc_scsi_send(uint8_t dev_addr, uint8_t lun, bool is_direction_in,
 //                                  uint8_t const * p_command, uint8_t cmd_len,
@@ -157,39 +144,9 @@ void tuh_msc_mounted_cb(uint8_t dev_addr);
  */
 void tuh_msc_unmounted_cb(uint8_t dev_addr);
 
-/** \brief      Callback function that is invoked when an transferring event occurred
- * \param[in]		dev_addr	Address of device
- * \param[in]   event an value from \ref xfer_result_t
- * \param[in]   xferred_bytes Number of bytes transferred via USB bus
- * \note        event can be one of following
- *              - XFER_RESULT_SUCCESS : previously scheduled transfer completes successfully.
- *              - XFER_RESULT_FAILED   : previously scheduled transfer encountered a transaction error.
- *              - XFER_RESULT_STALLED : previously scheduled transfer is stalled by device.
- * \note
- */
-void tuh_msc_isr(uint8_t dev_addr, xfer_result_t event, uint32_t xferred_bytes);
-
-
 //--------------------------------------------------------------------+
 // Internal Class Driver API
 //--------------------------------------------------------------------+
-typedef struct
-{
-  uint8_t  itf_num;
-  uint8_t  ep_in;
-  uint8_t  ep_out;
-
-  uint8_t  max_lun;
-  uint16_t block_size;
-  uint32_t last_lba; // last logical block address
-
-  volatile bool is_initialized;
-  uint8_t vendor_id[8];
-  uint8_t product_id[16];
-
-  msc_cbw_t cbw;
-  msc_csw_t csw;
-}msch_interface_t;
 
 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);
diff --git a/src/host/usbh_control.c b/src/host/usbh_control.c
index 70800eba6..de55bd5e1 100644
--- a/src/host/usbh_control.c
+++ b/src/host/usbh_control.c
@@ -88,7 +88,6 @@ bool usbh_control_xfer_cb (uint8_t dev_addr, uint8_t ep_addr, xfer_result_t resu
   (void) ep_addr;
   (void) xferred_bytes;
 
-
   usbh_device_t* dev = &_usbh_devices[dev_addr];
   const uint8_t rhport = dev->rhport;