diff --git a/demos/host/host_os_none/host_os_none.uvopt b/demos/host/host_os_none/host_os_none.uvopt
index 606ed51f4..cc4fd5522 100644
--- a/demos/host/host_os_none/host_os_none.uvopt
+++ b/demos/host/host_os_none/host_os_none.uvopt
@@ -185,12 +185,37 @@
           <WinNumber>1</WinNumber>
           <ItemText>ehci_data</ItemText>
         </Ww>
+        <Ww>
+          <count>5</count>
+          <WinNumber>1</WinNumber>
+          <ItemText>ehci_data.device[0].qhd[0]</ItemText>
+        </Ww>
+        <Ww>
+          <count>6</count>
+          <WinNumber>1</WinNumber>
+          <ItemText>ehci_data.device[0].qhd[1]</ItemText>
+        </Ww>
+        <Ww>
+          <count>7</count>
+          <WinNumber>1</WinNumber>
+          <ItemText>msch_semaphore</ItemText>
+        </Ww>
+        <Ww>
+          <count>8</count>
+          <WinNumber>1</WinNumber>
+          <ItemText>ehci_data.device[0].qhd[0].p_qtd_list_head</ItemText>
+        </Ww>
+        <Ww>
+          <count>9</count>
+          <WinNumber>1</WinNumber>
+          <ItemText>ehci_data.device[0].qhd[1].p_qtd_list_head</ItemText>
+        </Ww>
       </WatchWindow1>
       <MemoryWindow1>
         <Mm>
           <WinNumber>1</WinNumber>
           <SubType>0</SubType>
-          <ItemText>ITM_RxBuffer</ItemText>
+          <ItemText>0x20002067</ItemText>
         </Mm>
       </MemoryWindow1>
       <DebugFlag>
@@ -421,8 +446,8 @@
       <Focus>0</Focus>
       <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>1</TopLine>
-      <CurrentLine>1</CurrentLine>
+      <TopLine>101</TopLine>
+      <CurrentLine>107</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\src\main.c</PathWithFileName>
       <FilenameWithoutPath>main.c</FilenameWithoutPath>
@@ -437,8 +462,8 @@
       <Focus>0</Focus>
       <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>0</TopLine>
-      <CurrentLine>0</CurrentLine>
+      <TopLine>127</TopLine>
+      <CurrentLine>145</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\src\cdc_serial_app.c</PathWithFileName>
       <FilenameWithoutPath>cdc_serial_app.c</FilenameWithoutPath>
@@ -453,8 +478,8 @@
       <Focus>0</Focus>
       <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>0</TopLine>
-      <CurrentLine>0</CurrentLine>
+      <TopLine>169</TopLine>
+      <CurrentLine>186</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\src\keyboard_app.c</PathWithFileName>
       <FilenameWithoutPath>keyboard_app.c</FilenameWithoutPath>
@@ -469,8 +494,8 @@
       <Focus>0</Focus>
       <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>0</TopLine>
-      <CurrentLine>0</CurrentLine>
+      <TopLine>123</TopLine>
+      <CurrentLine>126</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\src\mouse_app.c</PathWithFileName>
       <FilenameWithoutPath>mouse_app.c</FilenameWithoutPath>
@@ -693,8 +718,8 @@
       <Focus>0</Focus>
       <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>0</TopLine>
-      <CurrentLine>0</CurrentLine>
+      <TopLine>58</TopLine>
+      <CurrentLine>76</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\..\..\tinyusb\tusb.c</PathWithFileName>
       <FilenameWithoutPath>tusb.c</FilenameWithoutPath>
@@ -755,10 +780,10 @@
       <FileType>1</FileType>
       <tvExp>0</tvExp>
       <Focus>0</Focus>
-      <ColumnNumber>48</ColumnNumber>
+      <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>367</TopLine>
-      <CurrentLine>374</CurrentLine>
+      <TopLine>493</TopLine>
+      <CurrentLine>501</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\..\..\tinyusb\host\usbh.c</PathWithFileName>
       <FilenameWithoutPath>usbh.c</FilenameWithoutPath>
@@ -771,10 +796,10 @@
       <FileType>1</FileType>
       <tvExp>0</tvExp>
       <Focus>0</Focus>
-      <ColumnNumber>27</ColumnNumber>
+      <ColumnNumber>0</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
-      <TopLine>1</TopLine>
-      <CurrentLine>8</CurrentLine>
+      <TopLine>593</TopLine>
+      <CurrentLine>605</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\..\..\tinyusb\host\ehci\ehci.c</PathWithFileName>
       <FilenameWithoutPath>ehci.c</FilenameWithoutPath>
@@ -931,10 +956,10 @@
       <FileType>1</FileType>
       <tvExp>0</tvExp>
       <Focus>0</Focus>
-      <ColumnNumber>0</ColumnNumber>
+      <ColumnNumber>44</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
       <TopLine>1</TopLine>
-      <CurrentLine>1</CurrentLine>
+      <CurrentLine>8</CurrentLine>
       <bDave2>0</bDave2>
       <PathWithFileName>..\..\..\tinyusb\class\msc_host.c</PathWithFileName>
       <FilenameWithoutPath>msc_host.c</FilenameWithoutPath>
@@ -1059,7 +1084,7 @@
       <FileType>2</FileType>
       <tvExp>0</tvExp>
       <Focus>0</Focus>
-      <ColumnNumber>9</ColumnNumber>
+      <ColumnNumber>18</ColumnNumber>
       <tvExpOptDlg>0</tvExpOptDlg>
       <TopLine>144</TopLine>
       <CurrentLine>150</CurrentLine>
diff --git a/tests/lpc18xx_43xx/test/host/usbh/test_enum_task.c b/tests/lpc18xx_43xx/test/host/usbh/test_enum_task.c
index 5d658449f..69b5bb40b 100644
--- a/tests/lpc18xx_43xx/test/host/usbh/test_enum_task.c
+++ b/tests/lpc18xx_43xx/test/host/usbh/test_enum_task.c
@@ -210,7 +210,7 @@ void test_addr0_failed_dev_desc(void)
 {
   osal_semaphore_wait_StubWithCallback(semaphore_wait_timeout_stub(0));
 
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
 
   usbh_enumeration_task(NULL);
 
@@ -222,7 +222,7 @@ void test_addr0_failed_set_address(void)
 {
   osal_semaphore_wait_StubWithCallback(semaphore_wait_timeout_stub(1));
   hcd_port_reset_Expect( usbh_devices[0].core_id );
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
 
   usbh_enumeration_task(NULL);
 
@@ -239,7 +239,7 @@ void test_enum_failed_get_full_dev_desc(void)
   osal_semaphore_reset_Expect( usbh_devices[0].control.sem_hdl );
   osal_mutex_reset_Expect( usbh_devices[0].control.mutex_hdl );
   hcd_pipe_control_open_ExpectAndReturn(1, desc_device.bMaxPacketSize0, TUSB_ERROR_NONE);
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
 
   usbh_enumeration_task(NULL);
 
@@ -261,7 +261,7 @@ void test_enum_failed_get_9byte_config_desc(void)
 
   hcd_pipe_control_open_ExpectAndReturn(1, desc_device.bMaxPacketSize0, TUSB_ERROR_NONE);
   tusbh_device_attached_cb_ExpectAndReturn((tusb_descriptor_device_t*) enum_data_buffer, 1);
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
 
   usbh_enumeration_task(NULL);
 
@@ -279,7 +279,7 @@ void test_enum_failed_get_full_config_desc(void)
   osal_mutex_reset_Expect( usbh_devices[0].control.mutex_hdl );
   hcd_pipe_control_open_ExpectAndReturn(1, desc_device.bMaxPacketSize0, TUSB_ERROR_NONE);
   tusbh_device_attached_cb_ExpectAndReturn((tusb_descriptor_device_t*) enum_data_buffer, 1);
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL);
 
   usbh_enumeration_task(NULL);
 }
@@ -294,7 +294,7 @@ void test_enum_parse_config_desc(void)
   hcd_pipe_control_open_ExpectAndReturn(1, desc_device.bMaxPacketSize0, TUSB_ERROR_NONE);
   tusbh_device_attached_cb_ExpectAndReturn((tusb_descriptor_device_t*) enum_data_buffer, 1);
 
-  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL); // fail to set configure
+//  tusbh_device_mount_failed_cb_Expect(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL); // fail to set configure
 
   usbh_enumeration_task(NULL);
 
diff --git a/tests/lpc18xx_43xx/test/host/usbh/test_usbh.c b/tests/lpc18xx_43xx/test/host/usbh/test_usbh.c
index 95e667a6a..961d836df 100644
--- a/tests/lpc18xx_43xx/test/host/usbh/test_usbh.c
+++ b/tests/lpc18xx_43xx/test/host/usbh/test_usbh.c
@@ -49,6 +49,7 @@
 #include "mock_tusb_callback.h"
 #include "mock_hid_host.h"
 #include "mock_cdc_host.h"
+#include "mock_msc_host.h"
 #include "host_helper.h"
 
 uint8_t dev_addr;
@@ -161,7 +162,7 @@ void test_usbh_device_unplugged_isr(void)
   usbh_devices[dev_addr].hub_port             = 0;
   usbh_devices[dev_addr].flag_supported_class = TUSB_CLASS_FLAG_HID;
 
-  helper_class_close_expect(dev_addr);
+  hidh_close_Expect(dev_addr);
   hcd_pipe_control_close_ExpectAndReturn(dev_addr, TUSB_ERROR_NONE);
 
   //------------- Code Under Test -------------//
@@ -170,6 +171,29 @@ void test_usbh_device_unplugged_isr(void)
   TEST_ASSERT_EQUAL(TUSB_DEVICE_STATE_REMOVING, usbh_devices[dev_addr].state);
 }
 
+void test_usbh_device_unplugged_multple_class(void)
+{
+  uint8_t dev_addr = 1;
+
+  usbh_devices[dev_addr].state                = TUSB_DEVICE_STATE_CONFIGURED;
+  usbh_devices[dev_addr].core_id              = 0;
+  usbh_devices[dev_addr].hub_addr             = 0;
+  usbh_devices[dev_addr].hub_port             = 0;
+  usbh_devices[dev_addr].flag_supported_class = TUSB_CLASS_FLAG_HID | TUSB_CLASS_FLAG_MSC | TUSB_CLASS_FLAG_CDC;
+
+  cdch_close_Expect(dev_addr);
+  hidh_close_Expect(dev_addr);
+  msch_close_Expect(dev_addr);
+
+  hcd_pipe_control_close_ExpectAndReturn(dev_addr, TUSB_ERROR_NONE);
+
+  //------------- Code Under Test -------------//
+  usbh_device_unplugged_isr(0);
+
+  TEST_ASSERT_EQUAL(TUSB_DEVICE_STATE_REMOVING, usbh_devices[dev_addr].state);
+
+}
+
 void semaphore_wait_success_stub(osal_mutex_handle_t const sem_hdl, uint32_t msec, tusb_error_t *p_error, int num_call)
 {
   (*p_error) = TUSB_ERROR_NONE;
@@ -219,3 +243,8 @@ void test_usbh_control_xfer_ok(void)
   //------------- Code Under Test -------------//
   usbh_control_xfer_subtask(dev_addr, 1, 2, 3, 4, 0, NULL);
 }
+
+//void test_usbh_xfer_isr_non_control_stalled(void) // do nothing for stall on control
+//{
+//
+//}
diff --git a/tinyusb/class/cdc_host.c b/tinyusb/class/cdc_host.c
index 15a232184..1fae8d66e 100644
--- a/tinyusb/class/cdc_host.c
+++ b/tinyusb/class/cdc_host.c
@@ -194,6 +194,7 @@ tusb_error_t cdch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
     {
       tusb_descriptor_endpoint_t const *p_endpoint = (tusb_descriptor_endpoint_t const *) p_desc;
       ASSERT_INT(TUSB_DESC_TYPE_ENDPOINT, p_endpoint->bDescriptorType, TUSB_ERROR_USBH_DESCRIPTOR_CORRUPTED);
+      ASSERT_INT(TUSB_XFER_BULK, p_endpoint->bmAttributes.xfer, TUSB_ERROR_USBH_DESCRIPTOR_CORRUPTED);
 
       pipe_handle_t * p_pipe_hdl =  ( p_endpoint->bEndpointAddress &  TUSB_DIR_DEV_TO_HOST_MASK ) ?
           &p_cdc->pipe_in : &p_cdc->pipe_out;
diff --git a/tinyusb/class/msc_host.c b/tinyusb/class/msc_host.c
index 1e11a4b85..9d4c9a258 100644
--- a/tinyusb/class/msc_host.c
+++ b/tinyusb/class/msc_host.c
@@ -53,6 +53,10 @@
 //--------------------------------------------------------------------+
 STATIC_VAR msch_interface_t msch_data[TUSB_CFG_HOST_DEVICE_MAX] TUSB_CFG_ATTR_USBRAM;
 
+//------------- Initalization Data -------------//
+OSAL_SEM_DEF(msch_semaphore);
+static osal_semaphore_handle_t msch_sem_hdl;
+
 // buffer used to read scsi information when mounted, largest reponse data currently is inquiry
 ATTR_ALIGNED(4) STATIC_VAR uint8_t msch_buffer[sizeof(scsi_inquiry_data_t)] TUSB_CFG_ATTR_USBRAM;
 
@@ -166,6 +170,7 @@ static tusb_error_t scsi_command_send(msch_interface_t * p_msch, scsi_cmd_type_t
 void msch_init(void)
 {
   memclr_(msch_data, sizeof(msch_interface_t)*TUSB_CFG_HOST_DEVICE_MAX);
+  msch_sem_hdl = osal_semaphore_create( OSAL_SEM_REF(msch_semaphore) );
 }
 
 tusb_error_t msch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t const *p_interface_desc, uint16_t *p_length)
@@ -185,6 +190,7 @@ tusb_error_t msch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
   for(uint32_t i=0; i<2; i++)
   {
     ASSERT_INT(TUSB_DESC_TYPE_ENDPOINT, p_endpoint->bDescriptorType, TUSB_ERROR_USBH_DESCRIPTOR_CORRUPTED);
+    ASSERT_INT(TUSB_XFER_BULK, p_endpoint->bmAttributes.xfer, TUSB_ERROR_USBH_DESCRIPTOR_CORRUPTED);
 
     pipe_handle_t * p_pipe_hdl =  ( p_endpoint->bEndpointAddress &  TUSB_DIR_DEV_TO_HOST_MASK ) ?
         &msch_data[dev_addr-1].bulk_in : &msch_data[dev_addr-1].bulk_out;
@@ -198,6 +204,7 @@ tusb_error_t msch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
   msch_data[dev_addr-1].interface_number = p_interface_desc->bInterfaceNumber;
   (*p_length) += sizeof(tusb_descriptor_interface_t) + 2*sizeof(tusb_descriptor_endpoint_t);
 
+
   //------------- Get Max Lun -------------//
   OSAL_SUBTASK_INVOKED_AND_WAIT(
     usbh_control_xfer_subtask( dev_addr, bm_request_type(TUSB_DIR_DEV_TO_HOST, TUSB_REQUEST_TYPE_CLASS, TUSB_REQUEST_RECIPIENT_INTERFACE),
@@ -219,26 +226,45 @@ tusb_error_t msch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
   );
 #endif
 
-
-  // TODO timeout required, a proper synchronization
-//  while( !hcd_pipe_is_idle(msch_data[dev_addr-1].bulk_in) )
-
+  enum { SCSI_XFER_TIMEOUT = 1000 };
   //------------- SCSI Inquiry -------------//
   scsi_command_send(&msch_data[dev_addr-1], SCSI_CMD_INQUIRY, 0, msch_buffer);
-  osal_task_delay(2);
+  osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT, &error);
+  SUBTASK_ASSERT_STATUS(error);
 
   memcpy(msch_data[dev_addr-1].vendor_id , ((scsi_inquiry_data_t*) msch_buffer)->vendor_id , 8);
   memcpy(msch_data[dev_addr-1].product_id, ((scsi_inquiry_data_t*) msch_buffer)->product_id, 16);
 
-#if 0
-  //------------- SCSI Request Sense -------------//
-  scsi_command_send(&msch_data[dev_addr-1], SCSI_CMD_REQUEST_SENSE, 0, msch_buffer);
-  osal_task_delay(2);
-#endif
-
   //------------- SCSI Read Capacity 10 -------------//
   scsi_command_send(&msch_data[dev_addr-1], SCSI_CMD_READ_CAPACITY_10, 0, msch_buffer);
-  osal_task_delay(2);
+  osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT, &error);
+  SUBTASK_ASSERT_STATUS(error);
+
+  // NOTE: my toshiba thumbdrive stall the first Read Capacity and require the sequence
+  // Read Capacity --> Stalled --> Clear Stall --> Request Sense --> Read Capacity (2) to work
+  if ( hcd_pipe_is_stalled(msch_data[dev_addr-1].bulk_in) )
+  { // clear stall TODO abtract clear stalll function
+    OSAL_SUBTASK_INVOKED_AND_WAIT(
+      usbh_control_xfer_subtask( dev_addr, bm_request_type(TUSB_DIR_HOST_TO_DEV, TUSB_REQUEST_TYPE_STANDARD, TUSB_REQUEST_RECIPIENT_ENDPOINT),
+                                 TUSB_REQUEST_CLEAR_FEATURE, 0, hcd_pipe_get_endpoint_addr(msch_data[dev_addr-1].bulk_in),
+                                 0, NULL ),
+      error
+    );
+
+    hcd_pipe_clear_stall(msch_data[dev_addr-1].bulk_in);
+    osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT, &error);
+    SUBTASK_ASSERT_STATUS(error);
+
+    //------------- SCSI Request Sense -------------//
+    scsi_command_send(&msch_data[dev_addr-1], SCSI_CMD_REQUEST_SENSE, 0, msch_buffer);
+    osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT, &error);
+    SUBTASK_ASSERT_STATUS(error);
+
+    //------------- Re-read SCSI Read Capactity -------------//
+    scsi_command_send(&msch_data[dev_addr-1], SCSI_CMD_READ_CAPACITY_10, 0, msch_buffer);
+    osal_semaphore_wait(msch_sem_hdl, SCSI_XFER_TIMEOUT, &error);
+    SUBTASK_ASSERT_STATUS(error);
+  }
 
   msch_data[dev_addr-1].last_lba   = __be2le( ((scsi_read_capacity10_data_t*)msch_buffer)->last_lba );
   msch_data[dev_addr-1].block_size = (uint16_t) __be2le( ((scsi_read_capacity10_data_t*)msch_buffer)->block_size );
@@ -252,7 +278,10 @@ tusb_error_t msch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
 
 void msch_isr(pipe_handle_t pipe_hdl, tusb_event_t event, uint32_t xferred_bytes)
 {
-
+  if ( pipehandle_is_equal(pipe_hdl, msch_data[pipe_hdl.dev_addr-1].bulk_in) )
+  {
+    osal_semaphore_post(msch_sem_hdl);
+  }
 }
 
 void msch_close(uint8_t dev_addr)
@@ -261,6 +290,7 @@ void msch_close(uint8_t dev_addr)
   (void) hcd_pipe_close(msch_data[dev_addr-1].bulk_out);
 
   memclr_(&msch_data[dev_addr-1], sizeof(msch_interface_t));
+  osal_semaphore_reset(msch_sem_hdl);
 }
 
 //--------------------------------------------------------------------+
diff --git a/tinyusb/common/errors.h b/tinyusb/common/errors.h
index 96681624c..77461f568 100644
--- a/tinyusb/common/errors.h
+++ b/tinyusb/common/errors.h
@@ -69,6 +69,8 @@
     ENTRY(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND   )\
     ENTRY(TUSB_ERROR_USBH_MOUNT_CONFIG_DESC_TOO_LONG )\
     ENTRY(TUSB_ERROR_USBH_DESCRIPTOR_CORRUPTED       )\
+    ENTRY(TUSB_ERROR_USBH_XFER_STALLED               )\
+    ENTRY(TUSB_ERROR_USBH_XFER_FAILED                )\
     ENTRY(TUSB_ERROR_OSAL_TIMEOUT                    )\
     ENTRY(TUSB_ERROR_OSAL_WAITING                    ) /* only used by OSAL_NONE in the subtask */ \
     ENTRY(TUSB_ERROR_OSAL_TASK_FAILED                )\
diff --git a/tinyusb/host/ehci/ehci.c b/tinyusb/host/ehci/ehci.c
index 40c59616e..684051917 100644
--- a/tinyusb/host/ehci/ehci.c
+++ b/tinyusb/host/ehci/ehci.c
@@ -100,6 +100,13 @@ static inline ehci_qhd_t*    qhd_find_free (uint8_t dev_addr) ATTR_PURE ATTR_ALW
 static inline tusb_xfer_type_t qhd_get_xfer_type(ehci_qhd_t const * p_qhd) ATTR_ALWAYS_INLINE ATTR_PURE;
 STATIC_ INLINE_ ehci_qhd_t*  qhd_get_from_pipe_handle(pipe_handle_t pipe_hdl) ATTR_PURE ATTR_ALWAYS_INLINE;
 static inline pipe_handle_t  qhd_create_pipe_handle(ehci_qhd_t const * p_qhd, tusb_xfer_type_t xfer_type) ATTR_PURE ATTR_ALWAYS_INLINE;
+// determine if a queue head has bus-related error
+static inline bool qhd_has_xact_error(ehci_qhd_t * p_qhd) ATTR_ALWAYS_INLINE ATTR_PURE;
+static inline bool qhd_has_xact_error(ehci_qhd_t * p_qhd)
+{
+  return ( p_qhd->qtd_overlay.buffer_err ||p_qhd->qtd_overlay.babble_err || p_qhd->qtd_overlay.xact_err );
+  //p_qhd->qtd_overlay.non_hs_period_missed_uframe || p_qhd->qtd_overlay.pingstate_err TODO split transaction error
+}
 
 static void qhd_init(ehci_qhd_t *p_qhd, uint8_t dev_addr, uint16_t max_packet_size, uint8_t endpoint_addr, uint8_t xfer_type, uint8_t interval);
 
@@ -468,12 +475,38 @@ tusb_error_t  hcd_pipe_close(pipe_handle_t pipe_hdl)
   return TUSB_ERROR_NONE;
 }
 
+bool hcd_pipe_is_busy(pipe_handle_t pipe_hdl)
+{
+  ehci_qhd_t *p_qhd = qhd_get_from_pipe_handle( pipe_hdl );
+  return !p_qhd->qtd_overlay.halted && (p_qhd->p_qtd_list_head != NULL);
+}
+
 bool hcd_pipe_is_idle(pipe_handle_t pipe_hdl)
 {
   ehci_qhd_t *p_qhd = qhd_get_from_pipe_handle( pipe_hdl );
   return (p_qhd->p_qtd_list_head == NULL);
 }
 
+bool hcd_pipe_is_stalled(pipe_handle_t pipe_hdl)
+{
+  ehci_qhd_t *p_qhd = qhd_get_from_pipe_handle( pipe_hdl );
+  return p_qhd->qtd_overlay.halted && !qhd_has_xact_error(p_qhd);
+}
+
+uint8_t hcd_pipe_get_endpoint_addr(pipe_handle_t pipe_hdl)
+{
+  ehci_qhd_t *p_qhd = qhd_get_from_pipe_handle( pipe_hdl );
+  return p_qhd->endpoint_number + ( (p_qhd->pid_non_control == EHCI_PID_IN) ? 0x80 : 0);
+}
+
+tusb_error_t hcd_pipe_clear_stall(pipe_handle_t pipe_hdl)
+{
+  ehci_qhd_t *p_qhd = qhd_get_from_pipe_handle( pipe_hdl );
+  p_qhd->qtd_overlay.halted = 0;
+
+  return TUSB_ERROR_NONE;
+}
+
 //--------------------------------------------------------------------+
 // EHCI Interrupt Handler
 //--------------------------------------------------------------------+
@@ -617,16 +650,14 @@ static void period_list_xfer_complete_isr(uint8_t hostid, uint8_t interval_ms)
 
 static void qhd_xfer_error_isr(ehci_qhd_t * p_qhd)
 {
-  if (  (p_qhd->device_address != 0 && p_qhd->qtd_overlay.halted)   || // addr0 cannot be protocol STALL
-      p_qhd->qtd_overlay.buffer_err ||p_qhd->qtd_overlay.babble_err || p_qhd->qtd_overlay.xact_err )
-    //p_qhd->qtd_overlay.non_hs_period_missed_uframe || p_qhd->qtd_overlay.pingstate_err TODO split transaction error
+  if ( (p_qhd->device_address != 0 && p_qhd->qtd_overlay.halted) || // addr0 cannot be protocol STALL
+        qhd_has_xact_error(p_qhd) )
   { // current qhd has error in transaction
     tusb_xfer_type_t const xfer_type = qhd_get_xfer_type(p_qhd);
     tusb_event_t error_event;
 
     // no error bits are set, endpoint is halted due to STALL
-    error_event = ( !(p_qhd->qtd_overlay.buffer_err || p_qhd->qtd_overlay.babble_err ||
-        p_qhd->qtd_overlay.xact_err) ) ? TUSB_EVENT_XFER_STALLED : TUSB_EVENT_XFER_ERROR;
+    error_event = qhd_has_xact_error(p_qhd) ? TUSB_EVENT_XFER_ERROR : TUSB_EVENT_XFER_STALLED;
 
     p_qhd->total_xferred_bytes += p_qhd->p_qtd_list_head->expected_bytes - p_qhd->p_qtd_list_head->total_bytes;
 
diff --git a/tinyusb/host/hcd.h b/tinyusb/host/hcd.h
index 61642d95b..6383015a8 100644
--- a/tinyusb/host/hcd.h
+++ b/tinyusb/host/hcd.h
@@ -98,7 +98,12 @@ pipe_handle_t hcd_pipe_open(uint8_t dev_addr, tusb_descriptor_endpoint_t const *
 tusb_error_t  hcd_pipe_queue_xfer(pipe_handle_t pipe_hdl, uint8_t buffer[], uint16_t total_bytes) ATTR_WARN_UNUSED_RESULT; // only queue, not transferring yet
 tusb_error_t  hcd_pipe_xfer(pipe_handle_t pipe_hdl, uint8_t buffer[], uint16_t total_bytes, bool int_on_complete)  ATTR_WARN_UNUSED_RESULT;
 tusb_error_t  hcd_pipe_close(pipe_handle_t pipe_hdl) /*ATTR_WARN_UNUSED_RESULT*/;
+
+bool hcd_pipe_is_busy(pipe_handle_t pipe_hdl);
+bool hcd_pipe_is_stalled(pipe_handle_t pipe_hdl);
 bool hcd_pipe_is_idle(pipe_handle_t pipe_hdl);
+uint8_t hcd_pipe_get_endpoint_addr(pipe_handle_t pipe_hdl);
+tusb_error_t hcd_pipe_clear_stall(pipe_handle_t pipe_hdl);
 
 #if 0
 tusb_error_t hcd_pipe_cancel()ATTR_WARN_UNUSED_RESULT;
diff --git a/tinyusb/host/usbh.c b/tinyusb/host/usbh.c
index 67cc8f96c..65efe8768 100644
--- a/tinyusb/host/usbh.c
+++ b/tinyusb/host/usbh.c
@@ -216,9 +216,13 @@ tusb_error_t usbh_control_xfer_subtask(uint8_t dev_addr, uint8_t bmRequestType,
   osal_mutex_release(usbh_devices[dev_addr].control.mutex_hdl);
 
   // TODO make handler for this function general purpose
-  SUBTASK_ASSERT_WITH_HANDLER(TUSB_ERROR_NONE == error &&
-                              TUSB_EVENT_XFER_COMPLETE == usbh_devices[dev_addr].control.pipe_status,
-                              tusbh_device_mount_failed_cb(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL) );
+  if (TUSB_ERROR_NONE != error)   SUBTASK_EXIT(error);
+  if (TUSB_EVENT_XFER_STALLED == usbh_devices[dev_addr].control.pipe_status) SUBTASK_EXIT(TUSB_ERROR_USBH_XFER_STALLED);
+  if (TUSB_EVENT_XFER_ERROR   == usbh_devices[dev_addr].control.pipe_status) SUBTASK_EXIT(TUSB_ERROR_USBH_XFER_FAILED);
+
+//  SUBTASK_ASSERT_WITH_HANDLER(TUSB_ERROR_NONE == error &&
+//                              TUSB_EVENT_XFER_COMPLETE == usbh_devices[dev_addr].control.pipe_status,
+//                              tusbh_device_mount_failed_cb(TUSB_ERROR_USBH_MOUNT_DEVICE_NOT_RESPOND, NULL) );
 
   OSAL_SUBTASK_END
 }
diff --git a/tinyusb/osal/osal.h b/tinyusb/osal/osal.h
index d2287b3a5..d23cb518c 100644
--- a/tinyusb/osal/osal.h
+++ b/tinyusb/osal/osal.h
@@ -68,16 +68,20 @@
 
 #if TUSB_CFG_OS == TUSB_OS_NONE
   #include "osal_none.h"
-#elif TUSB_CFG_OS == TUSB_OS_FREERTOS
-  #include "osal_freeRTOS.h"
-#elif TUSB_CFG_OS == TUSB_OS_CMSIS_RTX
-  #include "osal_cmsis_rtx.h"
 #else
-  #error TUSB_CFG_OS is not defined or OS is not supported yet
+  #define OSAL_VAR
+  #if TUSB_CFG_OS == TUSB_OS_FREERTOS
+    #include "osal_freeRTOS.h"
+  #elif TUSB_CFG_OS == TUSB_OS_CMSIS_RTX
+    #include "osal_cmsis_rtx.h"
+  #else
+    #error TUSB_CFG_OS is not defined or OS is not supported yet
+  #endif
 #endif
 
 #else // OSAL API for cmock
 
+#define OSAL_VAR
 #include "osal_common.h"
 
 //------------- Tick -------------//
diff --git a/tinyusb/osal/osal_none.h b/tinyusb/osal/osal_none.h
index 853f33e67..775febc3f 100644
--- a/tinyusb/osal/osal_none.h
+++ b/tinyusb/osal/osal_none.h
@@ -58,6 +58,9 @@
  extern "C" {
 #endif
 
+// variable that retains value after OSAL blocking service need to declare with OSAL_VAR
+#define OSAL_VAR  static
+
 //--------------------------------------------------------------------+
 // TICK API
 //--------------------------------------------------------------------+