diff --git a/demos/host/host_bulk_xfer/main.c b/demos/host/host_bulk_xfer/main.c
index 7c20c4f30..8ce7ef6b4 100644
--- a/demos/host/host_bulk_xfer/main.c
+++ b/demos/host/host_bulk_xfer/main.c
@@ -112,12 +112,18 @@ int main(void)
 // BLINKING TASK
 //--------------------------------------------------------------------+
 uint8_t custom_read_buffer[4*1024] TUSB_CFG_ATTR_USBRAM;
-uint8_t custom_write_buffer[4*1024] TUSB_CFG_ATTR_USBRAM;
+uint32_t custom_write_buffer[1024] TUSB_CFG_ATTR_USBRAM;
 void custom_class_loopback_task (void* p_task_para)
 {
   if( tusbh_custom_is_mounted(1, 0, 0) ) // hardcode addr = 1, ignore vendor/product ID
   {
     tusbh_custom_read(1, 0, 0, custom_read_buffer, sizeof(custom_read_buffer));
+
+    static uint32_t magic_number = 1;
+    custom_write_buffer[0] = magic_number;
+    tusbh_custom_write(1, 0, 0, custom_write_buffer, sizeof(custom_write_buffer));
+
+    magic_number += 2;
   }
 }
 
diff --git a/tinyusb/class/custom_class_host.c b/tinyusb/class/custom_class_host.c
index e0f9ce5b0..39d4c260a 100644
--- a/tinyusb/class/custom_class_host.c
+++ b/tinyusb/class/custom_class_host.c
@@ -57,10 +57,7 @@
 //--------------------------------------------------------------------+
 custom_interface_info_t custom_interface[TUSB_CFG_HOST_DEVICE_MAX];
 
-//--------------------------------------------------------------------+
-// APPLICATION API
-//--------------------------------------------------------------------+
-tusb_error_t tusbh_custom_read(uint8_t dev_addr, uint16_t vendor_id, uint16_t product_id, void * p_buffer, uint16_t length)
+static tusb_error_t cush_validate_paras(uint8_t dev_addr, uint16_t vendor_id, uint16_t product_id, void * p_buffer, uint16_t length)
 {
   if ( !tusbh_custom_is_mounted(dev_addr, vendor_id, product_id) )
   {
@@ -68,6 +65,16 @@ tusb_error_t tusbh_custom_read(uint8_t dev_addr, uint16_t vendor_id, uint16_t pr
   }
 
   ASSERT( p_buffer != NULL && length != 0, TUSB_ERROR_INVALID_PARA);
+
+  return TUSB_ERROR_NONE;
+}
+//--------------------------------------------------------------------+
+// APPLICATION API (need to check parameters)
+//--------------------------------------------------------------------+
+tusb_error_t tusbh_custom_read(uint8_t dev_addr, uint16_t vendor_id, uint16_t product_id, void * p_buffer, uint16_t length)
+{
+  ASSERT_STATUS( cush_validate_paras(dev_addr, vendor_id, product_id, p_buffer, length) );
+
   if ( !hcd_pipe_is_idle(custom_interface[dev_addr-1].pipe_in) )
   {
     return TUSB_ERROR_INTERFACE_IS_BUSY;
@@ -80,6 +87,15 @@ tusb_error_t tusbh_custom_read(uint8_t dev_addr, uint16_t vendor_id, uint16_t pr
 
 tusb_error_t tusbh_custom_write(uint8_t dev_addr, uint16_t vendor_id, uint16_t product_id, void const * p_data, uint16_t length)
 {
+  ASSERT_STATUS( cush_validate_paras(dev_addr, vendor_id, product_id, p_data, length) );
+
+  if ( !hcd_pipe_is_idle(custom_interface[dev_addr-1].pipe_out) )
+  {
+    return TUSB_ERROR_INTERFACE_IS_BUSY;
+  }
+
+  (void) hcd_pipe_xfer( custom_interface[dev_addr-1].pipe_out, p_data, length, true);
+
   return TUSB_ERROR_NONE;
 }
 
diff --git a/tinyusb/host/ehci/ehci.c b/tinyusb/host/ehci/ehci.c
index 89e5ab57b..0a15f9355 100644
--- a/tinyusb/host/ehci/ehci.c
+++ b/tinyusb/host/ehci/ehci.c
@@ -456,7 +456,7 @@ bool hcd_pipe_is_idle(pipe_handle_t pipe_hdl)
 void async_advance_isr(ehci_qhd_t * const async_head)
 {
   // TODO do we need to close addr0
-  if(async_head->is_removing) // closing control pipe of addr0
+  if (async_head->is_removing) // closing control pipe of addr0
   {
     async_head->is_removing        = 0;
     async_head->p_qtd_list_head    = async_head->p_qtd_list_tail = NULL;
@@ -469,17 +469,17 @@ void async_advance_isr(ehci_qhd_t * const async_head)
   {
     // check if control endpoint is removing
     ehci_qhd_t *p_control_qhd = &ehci_data.device[relative_dev_addr].control.qhd;
-    if( p_control_qhd->is_removing )
+    if ( p_control_qhd->is_removing )
     {
-      p_control_qhd->is_removing     = 0;
-      p_control_qhd->used            = 0;
+      p_control_qhd->is_removing = 0;
+      p_control_qhd->used        = 0;
 
       // Host Controller has cleaned up its cached data for this device, set state to unplug
       usbh_devices[relative_dev_addr+1].state = TUSB_DEVICE_STATE_UNPLUG;
 
       for (uint8_t i=0; i<EHCI_MAX_QHD; i++) // free all qhd
       {
-        ehci_data.device[relative_dev_addr].qhd[i].used = 0;
+        ehci_data.device[relative_dev_addr].qhd[i].used        = 0;
         ehci_data.device[relative_dev_addr].qhd[i].is_removing = 0;
       }
       for (uint8_t i=0; i<EHCI_MAX_QTD; i++) // free all qtd