Merge remote-tracking branch 'tinyusb/master' into copilot/fix-dcd-edpt-xfer-issue

Signed-off-by: HiFiPhile <[email protected]>

9 files changed, 531 insertions, 691 deletions

diff --git a/src/class/cdc/cdc_device.c b/src/class/cdc/cdc_device.c
index bf631908f..9e62c6509 100644
--- a/src/class/cdc/cdc_device.c
+++ b/src/class/cdc/cdc_device.c
@@ -48,28 +48,23 @@
 typedef struct {
   uint8_t rhport;
   uint8_t itf_num;
-  uint8_t ep_in;
-  uint8_t ep_out;
-
   uint8_t ep_notify;
   uint8_t line_state; // Bit 0: DTR, Bit 1: RTS
 
   /*------------- From this point, data is not cleared by bus reset -------------*/
-  char wanted_char;
   TU_ATTR_ALIGNED(4) cdc_line_coding_t line_coding;
+  char wanted_char;
 
-  // FIFO
-  tu_fifo_t rx_ff;
-  tu_fifo_t tx_ff;
-
-  uint8_t rx_ff_buf[CFG_TUD_CDC_RX_BUFSIZE];
-  uint8_t tx_ff_buf[CFG_TUD_CDC_TX_BUFSIZE];
+  struct {
+    tu_edpt_stream_t tx;
+    tu_edpt_stream_t rx;
 
-  OSAL_MUTEX_DEF(rx_ff_mutex);
-  OSAL_MUTEX_DEF(tx_ff_mutex);
+    uint8_t tx_ff_buf[CFG_TUD_CDC_TX_BUFSIZE];
+    uint8_t rx_ff_buf[CFG_TUD_CDC_RX_BUFSIZE];
+  } stream;
 } cdcd_interface_t;
 
-#define ITF_MEM_RESET_SIZE   offsetof(cdcd_interface_t, wanted_char)
+#define ITF_MEM_RESET_SIZE offsetof(cdcd_interface_t, line_coding)
 
 typedef struct {
   TUD_EPBUF_DEF(epout, CFG_TUD_CDC_EP_BUFSIZE);
@@ -81,110 +76,100 @@ typedef struct {
 } cdcd_epbuf_t;
 
 //--------------------------------------------------------------------+
-// INTERNAL OBJECT & FUNCTION DECLARATION
-//--------------------------------------------------------------------+
-static cdcd_interface_t _cdcd_itf[CFG_TUD_CDC];
-CFG_TUD_MEM_SECTION static cdcd_epbuf_t _cdcd_epbuf[CFG_TUD_CDC];
-
-static tud_cdc_configure_t _cdcd_cfg = TUD_CDC_CONFIGURE_DEFAULT();
-
-static bool _prep_out_transaction(uint8_t itf) {
-  const uint8_t rhport = 0;
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  cdcd_epbuf_t* p_epbuf = &_cdcd_epbuf[itf];
-
-  // Skip if usb is not ready yet
-  TU_VERIFY(tud_ready() && p_cdc->ep_out);
-
-  uint16_t available = tu_fifo_remaining(&p_cdc->rx_ff);
-
-  // Prepare for incoming data but only allow what we can store in the ring buffer.
-  // TODO Actually we can still carry out the transfer, keeping count of received bytes
-  // and slowly move it to the FIFO when read().
-  // This pre-check reduces endpoint claiming
-  TU_VERIFY(available >= CFG_TUD_CDC_EP_BUFSIZE);
-
-  // claim endpoint
-  TU_VERIFY(usbd_edpt_claim(p_cdc->rhport, p_cdc->ep_out));
-
-  // fifo can be changed before endpoint is claimed
-  available = tu_fifo_remaining(&p_cdc->rx_ff);
-
-  if (available >= CFG_TUD_CDC_EP_BUFSIZE) {
-    return usbd_edpt_xfer(rhport, p_cdc->ep_out, p_epbuf->epout, CFG_TUD_CDC_EP_BUFSIZE, false);
-  } else {
-    // Release endpoint since we don't make any transfer
-    usbd_edpt_release(p_cdc->rhport, p_cdc->ep_out);
-    return false;
-  }
-}
-
-//--------------------------------------------------------------------+
 // Weak stubs: invoked if no strong implementation is available
 //--------------------------------------------------------------------+
 TU_ATTR_WEAK void tud_cdc_rx_cb(uint8_t itf) {
-  (void) itf;
+  (void)itf;
 }
 
 TU_ATTR_WEAK void tud_cdc_rx_wanted_cb(uint8_t itf, char wanted_char) {
-  (void) itf;
-  (void) wanted_char;
+  (void)itf;
+  (void)wanted_char;
 }
 
 TU_ATTR_WEAK void tud_cdc_tx_complete_cb(uint8_t itf) {
-  (void) itf;
+  (void)itf;
 }
 
 TU_ATTR_WEAK void tud_cdc_notify_complete_cb(uint8_t itf) {
-  (void) itf;
+  (void)itf;
 }
 
 TU_ATTR_WEAK void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
-  (void) itf;
-  (void) dtr;
-  (void) rts;
+  (void)itf;
+  (void)dtr;
+  (void)rts;
 }
 
-TU_ATTR_WEAK void tud_cdc_line_coding_cb(uint8_t itf, cdc_line_coding_t const* p_line_coding) {
-  (void) itf;
-  (void) p_line_coding;
+TU_ATTR_WEAK void tud_cdc_line_coding_cb(uint8_t itf, const cdc_line_coding_t *p_line_coding) {
+  (void)itf;
+  (void)p_line_coding;
 }
 
 TU_ATTR_WEAK void tud_cdc_send_break_cb(uint8_t itf, uint16_t duration_ms) {
-  (void) itf;
-  (void) duration_ms;
+  (void)itf;
+  (void)duration_ms;
+}
+
+//--------------------------------------------------------------------+
+// INTERNAL OBJECT & FUNCTION DECLARATION
+//--------------------------------------------------------------------+
+static cdcd_interface_t _cdcd_itf[CFG_TUD_CDC];
+CFG_TUD_MEM_SECTION static cdcd_epbuf_t _cdcd_epbuf[CFG_TUD_CDC];
+static tud_cdc_configure_t _cdcd_cfg = TUD_CDC_CONFIGURE_DEFAULT();
+
+TU_ATTR_ALWAYS_INLINE static inline uint8_t find_cdc_itf(uint8_t ep_addr) {
+  for (uint8_t idx = 0; idx < CFG_TUD_CDC; idx++) {
+    const cdcd_interface_t *p_cdc = &_cdcd_itf[idx];
+    if (ep_addr == p_cdc->stream.rx.ep_addr || ep_addr == p_cdc->stream.tx.ep_addr ||
+        (ep_addr == p_cdc->ep_notify && ep_addr != 0)) {
+      return idx;
+    }
+  }
+  return TUSB_INDEX_INVALID_8;
 }
 
 //--------------------------------------------------------------------+
 // APPLICATION API
 //--------------------------------------------------------------------+
 bool tud_cdc_configure(const tud_cdc_configure_t* driver_cfg) {
-  TU_VERIFY(driver_cfg);
+  TU_VERIFY(driver_cfg != NULL);
   _cdcd_cfg = *driver_cfg;
   return true;
 }
 
 bool tud_cdc_n_ready(uint8_t itf) {
-  return tud_ready() && _cdcd_itf[itf].ep_in != 0 && _cdcd_itf[itf].ep_out != 0;
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  TU_VERIFY(tud_ready());
+  const cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+
+  const bool in_opened  = tu_edpt_stream_is_opened(&p_cdc->stream.tx);
+  const bool out_opened = tu_edpt_stream_is_opened(&p_cdc->stream.rx);
+  return in_opened && out_opened;
 }
 
 bool tud_cdc_n_connected(uint8_t itf) {
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  TU_VERIFY(tud_ready());
   // DTR (bit 0) active  is considered as connected
-  return tud_ready() && tu_bit_test(_cdcd_itf[itf].line_state, 0);
+  return tu_bit_test(_cdcd_itf[itf].line_state, 0);
 }
 
 uint8_t tud_cdc_n_get_line_state(uint8_t itf) {
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
   return _cdcd_itf[itf].line_state;
 }
 
-void tud_cdc_n_get_line_coding(uint8_t itf, cdc_line_coding_t* coding) {
+void tud_cdc_n_get_line_coding(uint8_t itf, cdc_line_coding_t *coding) {
+  TU_VERIFY(itf < CFG_TUD_CDC, );
   (*coding) = _cdcd_itf[itf].line_coding;
 }
 
 #if CFG_TUD_CDC_NOTIFY
 bool tud_cdc_n_notify_uart_state (uint8_t itf, const cdc_notify_uart_state_t *state) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  cdcd_epbuf_t* p_epbuf = &_cdcd_epbuf[itf];
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  cdcd_interface_t *p_cdc   = &_cdcd_itf[itf];
+  cdcd_epbuf_t     *p_epbuf = &_cdcd_epbuf[itf];
   TU_VERIFY(tud_ready() && p_cdc->ep_notify != 0);
   TU_VERIFY(usbd_edpt_claim(p_cdc->rhport, p_cdc->ep_notify));
 
@@ -200,8 +185,9 @@ bool tud_cdc_n_notify_uart_state (uint8_t itf, const cdc_notify_uart_state_t *st
 }
 
 bool tud_cdc_n_notify_conn_speed_change(uint8_t itf, const cdc_notify_conn_speed_change_t* conn_speed_change) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  cdcd_epbuf_t* p_epbuf = &_cdcd_epbuf[itf];
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  cdcd_interface_t *p_cdc   = &_cdcd_itf[itf];
+  cdcd_epbuf_t     *p_epbuf = &_cdcd_epbuf[itf];
   TU_VERIFY(tud_ready() && p_cdc->ep_notify != 0);
   TU_VERIFY(usbd_edpt_claim(p_cdc->rhport, p_cdc->ep_notify));
 
@@ -218,6 +204,7 @@ bool tud_cdc_n_notify_conn_speed_change(uint8_t itf, const cdc_notify_conn_speed
 #endif
 
 void tud_cdc_n_set_wanted_char(uint8_t itf, char wanted) {
+  TU_VERIFY(itf < CFG_TUD_CDC, );
   _cdcd_itf[itf].wanted_char = wanted;
 }
 
@@ -225,77 +212,53 @@ void tud_cdc_n_set_wanted_char(uint8_t itf, char wanted) {
 // READ API
 //--------------------------------------------------------------------+
 uint32_t tud_cdc_n_available(uint8_t itf) {
-  return tu_fifo_count(&_cdcd_itf[itf].rx_ff);
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
+  return tu_edpt_stream_read_available(&_cdcd_itf[itf].stream.rx);
 }
 
 uint32_t tud_cdc_n_read(uint8_t itf, void* buffer, uint32_t bufsize) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  uint32_t num_read = tu_fifo_read_n(&p_cdc->rx_ff, buffer, (uint16_t) TU_MIN(bufsize, UINT16_MAX));
-  _prep_out_transaction(itf);
-  return num_read;
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  return tu_edpt_stream_read(p_cdc->rhport, &p_cdc->stream.rx, buffer, bufsize);
 }
 
-bool tud_cdc_n_peek(uint8_t itf, uint8_t* chr) {
-  return tu_fifo_peek(&_cdcd_itf[itf].rx_ff, chr);
+bool tud_cdc_n_peek(uint8_t itf, uint8_t *chr) {
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  return tu_edpt_stream_peek(&_cdcd_itf[itf].stream.rx, chr);
 }
 
 void tud_cdc_n_read_flush(uint8_t itf) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  tu_fifo_clear(&p_cdc->rx_ff);
-  _prep_out_transaction(itf);
+  TU_VERIFY(itf < CFG_TUD_CDC, );
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  tu_edpt_stream_clear(&p_cdc->stream.rx);
+  tu_edpt_stream_read_xfer(p_cdc->rhport, &p_cdc->stream.rx);
 }
 
 //--------------------------------------------------------------------+
 // WRITE API
 //--------------------------------------------------------------------+
 uint32_t tud_cdc_n_write(uint8_t itf, const void* buffer, uint32_t bufsize) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  uint16_t wr_count = tu_fifo_write_n(&p_cdc->tx_ff, buffer, (uint16_t) TU_MIN(bufsize, UINT16_MAX));
-
-  // flush if queue more than packet size
-  if (tu_fifo_count(&p_cdc->tx_ff) >= BULK_PACKET_SIZE
-      #if CFG_TUD_CDC_TX_BUFSIZE < BULK_PACKET_SIZE
-      || tu_fifo_full(&p_cdc->tx_ff) // check full if fifo size is less than packet size
-      #endif
-      ) {
-    tud_cdc_n_write_flush(itf);
-  }
-
-  return wr_count;
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  return tu_edpt_stream_write(p_cdc->rhport, &p_cdc->stream.tx, buffer, bufsize);
 }
 
 uint32_t tud_cdc_n_write_flush(uint8_t itf) {
-  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  cdcd_epbuf_t* p_epbuf = &_cdcd_epbuf[itf];
-  TU_VERIFY(tud_ready(), 0); // Skip if usb is not ready yet
-
-  // No data to send
-  if (0 == tu_fifo_count(&p_cdc->tx_ff)) {
-    return 0;
-  }
-
-  TU_VERIFY(usbd_edpt_claim(p_cdc->rhport, p_cdc->ep_in), 0); // Claim the endpoint
-
-  // Pull data from FIFO
-  const uint16_t count = tu_fifo_read_n(&p_cdc->tx_ff, p_epbuf->epin, CFG_TUD_CDC_EP_BUFSIZE);
-
-  if (count > 0) {
-    TU_ASSERT(usbd_edpt_xfer(p_cdc->rhport, p_cdc->ep_in, p_epbuf->epin, count, false), 0);
-    return count;
-  } else {
-    // Release endpoint since we don't make any transfer
-    // Note: data is dropped if terminal is not connected
-    usbd_edpt_release(p_cdc->rhport, p_cdc->ep_in);
-    return 0;
-  }
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  return tu_edpt_stream_write_xfer(p_cdc->rhport, &p_cdc->stream.tx);
 }
 
 uint32_t tud_cdc_n_write_available(uint8_t itf) {
-  return tu_fifo_remaining(&_cdcd_itf[itf].tx_ff);
+  TU_VERIFY(itf < CFG_TUD_CDC, 0);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  return tu_edpt_stream_write_available(p_cdc->rhport, &p_cdc->stream.tx);
 }
 
 bool tud_cdc_n_write_clear(uint8_t itf) {
-  return tu_fifo_clear(&_cdcd_itf[itf].tx_ff);
+  TU_VERIFY(itf < CFG_TUD_CDC);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[itf];
+  return tu_edpt_stream_clear(&p_cdc->stream.tx);
 }
 
 //--------------------------------------------------------------------+
@@ -304,7 +267,8 @@ bool tud_cdc_n_write_clear(uint8_t itf) {
 void cdcd_init(void) {
   tu_memclr(_cdcd_itf, sizeof(_cdcd_itf));
   for (uint8_t i = 0; i < CFG_TUD_CDC; i++) {
-    cdcd_interface_t* p_cdc = &_cdcd_itf[i];
+    cdcd_interface_t *p_cdc   = &_cdcd_itf[i];
+    cdcd_epbuf_t     *p_epbuf = &_cdcd_epbuf[i];
 
     p_cdc->wanted_char = (char) -1;
 
@@ -314,44 +278,23 @@ void cdcd_init(void) {
     p_cdc->line_coding.parity = 0;
     p_cdc->line_coding.data_bits = 8;
 
-    // Config RX fifo
-    tu_fifo_config(&p_cdc->rx_ff, p_cdc->rx_ff_buf, TU_ARRAY_SIZE(p_cdc->rx_ff_buf), 1, false);
+    tu_edpt_stream_init(&p_cdc->stream.rx, false, false, false, p_cdc->stream.rx_ff_buf, CFG_TUD_CDC_RX_BUFSIZE,
+                        p_epbuf->epout, CFG_TUD_CDC_EP_BUFSIZE);
 
     // TX fifo can be configured to change to overwritable if not connected (DTR bit not set). Without DTR we do not
     // know if data is actually polled by terminal. This way the most current data is prioritized.
     // Default: is overwritable
-    tu_fifo_config(&p_cdc->tx_ff, p_cdc->tx_ff_buf, TU_ARRAY_SIZE(p_cdc->tx_ff_buf), 1, _cdcd_cfg.tx_overwritabe_if_not_connected);
-
-    #if OSAL_MUTEX_REQUIRED
-    osal_mutex_t mutex_rd = osal_mutex_create(&p_cdc->rx_ff_mutex);
-    osal_mutex_t mutex_wr = osal_mutex_create(&p_cdc->tx_ff_mutex);
-    TU_ASSERT(mutex_rd != NULL && mutex_wr != NULL, );
-
-    tu_fifo_config_mutex(&p_cdc->rx_ff, NULL, mutex_rd);
-    tu_fifo_config_mutex(&p_cdc->tx_ff, mutex_wr, NULL);
-    #endif
+    tu_edpt_stream_init(&p_cdc->stream.tx, false, true, _cdcd_cfg.tx_overwritabe_if_not_connected,
+                        p_cdc->stream.tx_ff_buf, CFG_TUD_CDC_TX_BUFSIZE, p_epbuf->epin, CFG_TUD_CDC_EP_BUFSIZE);
   }
 }
 
 bool cdcd_deinit(void) {
-  #if OSAL_MUTEX_REQUIRED
-  for(uint8_t i=0; i<CFG_TUD_CDC; i++) {
+  for (uint8_t i = 0; i < CFG_TUD_CDC; i++) {
     cdcd_interface_t* p_cdc = &_cdcd_itf[i];
-    const osal_mutex_t mutex_rd = p_cdc->rx_ff.mutex_rd;
-    const osal_mutex_t mutex_wr = p_cdc->tx_ff.mutex_wr;
-
-    if (mutex_rd != NULL) {
-      osal_mutex_delete(mutex_rd);
-      tu_fifo_config_mutex(&p_cdc->rx_ff, NULL, NULL);
-    }
-
-    if (mutex_wr != NULL) {
-      osal_mutex_delete(mutex_wr);
-      tu_fifo_config_mutex(&p_cdc->tx_ff, NULL, NULL);
-    }
+    tu_edpt_stream_deinit(&p_cdc->stream.rx);
+    tu_edpt_stream_deinit(&p_cdc->stream.tx);
   }
-  #endif
-
   return true;
 }
 
@@ -360,74 +303,85 @@ void cdcd_reset(uint8_t rhport) {
 
   for (uint8_t i = 0; i < CFG_TUD_CDC; i++) {
     cdcd_interface_t* p_cdc = &_cdcd_itf[i];
-
     tu_memclr(p_cdc, ITF_MEM_RESET_SIZE);
-    if (!_cdcd_cfg.rx_persistent) {
-      tu_fifo_clear(&p_cdc->rx_ff);
-    }
-    if (!_cdcd_cfg.tx_persistent) {
-      tu_fifo_clear(&p_cdc->tx_ff);
-    }
-    tu_fifo_set_overwritable(&p_cdc->tx_ff, _cdcd_cfg.tx_overwritabe_if_not_connected);
+
+    tu_fifo_set_overwritable(&p_cdc->stream.tx.ff, _cdcd_cfg.tx_overwritabe_if_not_connected); // back to default
+    tu_edpt_stream_close(&p_cdc->stream.rx);
+    tu_edpt_stream_close(&p_cdc->stream.tx);
   }
 }
 
 uint16_t cdcd_open(uint8_t rhport, const tusb_desc_interface_t* itf_desc, uint16_t max_len) {
   // Only support ACM subclass
-  TU_VERIFY( TUSB_CLASS_CDC                           == itf_desc->bInterfaceClass &&
-             CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL == itf_desc->bInterfaceSubClass, 0);
+  TU_VERIFY(TUSB_CLASS_CDC == itf_desc->bInterfaceClass &&
+              CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL == itf_desc->bInterfaceSubClass,
+            0);
 
-  // Find available interface
-  cdcd_interface_t* p_cdc;
-  uint8_t cdc_id;
-  for (cdc_id = 0; cdc_id < CFG_TUD_CDC; cdc_id++) {
-    p_cdc = &_cdcd_itf[cdc_id];
-    if (p_cdc->ep_in == 0) {
-      break;
-    }
-  }
+  const uint8_t cdc_id = find_cdc_itf(0); // Find available interface
   TU_ASSERT(cdc_id < CFG_TUD_CDC, 0);
+  cdcd_interface_t *p_cdc = &_cdcd_itf[cdc_id];
 
   //------------- Control Interface -------------//
   p_cdc->rhport = rhport;
   p_cdc->itf_num = itf_desc->bInterfaceNumber;
 
-  uint16_t drv_len = sizeof(tusb_desc_interface_t);
-  const uint8_t* p_desc = tu_desc_next(itf_desc);
+  const uint8_t *p_desc   = (const uint8_t *)itf_desc;
+  const uint8_t *desc_end = p_desc + max_len;
 
-  // Communication Functional Descriptors
-  while (TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc) && drv_len <= max_len) {
-    drv_len += tu_desc_len(p_desc);
+  // Skip all class-specific descriptor
+  p_desc = tu_desc_next(itf_desc);
+  while (tu_desc_in_bounds(p_desc, desc_end) && TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc)) {
     p_desc = tu_desc_next(p_desc);
   }
 
+  // notification endpoint (optional)
   if (TUSB_DESC_ENDPOINT == tu_desc_type(p_desc)) {
-    // notification endpoint
     const tusb_desc_endpoint_t* desc_ep = (const tusb_desc_endpoint_t*) p_desc;
     TU_ASSERT(usbd_edpt_open(rhport, desc_ep), 0);
     p_cdc->ep_notify = desc_ep->bEndpointAddress;
 
-    drv_len += tu_desc_len(p_desc);
     p_desc = tu_desc_next(p_desc);
   }
 
-  //------------- Data Interface (if any) -------------//
-  if ((TUSB_DESC_INTERFACE == tu_desc_type(p_desc)) &&
-      (TUSB_CLASS_CDC_DATA == ((const tusb_desc_interface_t*) p_desc)->bInterfaceClass)) {
-    // next to endpoint descriptor
-    drv_len += tu_desc_len(p_desc);
-    p_desc = tu_desc_next(p_desc);
+  //------------- Data Interface (optional) -------------//
+  if (TUSB_DESC_INTERFACE == tu_desc_type(p_desc)) {
+    const tusb_desc_interface_t *data_itf_desc = (const tusb_desc_interface_t *)p_desc;
+    if (TUSB_CLASS_CDC_DATA == data_itf_desc->bInterfaceClass) {
+      for (uint8_t e = 0; e < data_itf_desc->bNumEndpoints; e++) {
+        if (!tu_desc_in_bounds(p_desc, desc_end)) {
+          break;
+        }
+        p_desc = tu_desc_next(p_desc);
 
-    // Open endpoint pair
-    TU_ASSERT(usbd_open_edpt_pair(rhport, p_desc, 2, TUSB_XFER_BULK, &p_cdc->ep_out, &p_cdc->ep_in), 0);
+        const tusb_desc_endpoint_t *desc_ep = (const tusb_desc_endpoint_t *)p_desc;
+        TU_ASSERT(TUSB_DESC_ENDPOINT == desc_ep->bDescriptorType && TUSB_XFER_BULK == desc_ep->bmAttributes.xfer, 0);
 
-    drv_len += 2 * sizeof(tusb_desc_endpoint_t);
-  }
+        TU_ASSERT(usbd_edpt_open(rhport, desc_ep), 0);
+        if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN) {
+          tu_edpt_stream_t *stream_tx = &p_cdc->stream.tx;
+
+          tu_edpt_stream_open(stream_tx, desc_ep);
+          if (_cdcd_cfg.tx_persistent) {
+            tu_edpt_stream_write_xfer(rhport, stream_tx); // flush pending data
+          } else {
+            tu_edpt_stream_clear(stream_tx);
+          }
+        } else {
+          tu_edpt_stream_t *stream_rx = &p_cdc->stream.rx;
 
-  // Prepare for incoming data
-  _prep_out_transaction(cdc_id);
+          tu_edpt_stream_open(stream_rx, desc_ep);
+          if (!_cdcd_cfg.rx_persistent) {
+            tu_edpt_stream_clear(stream_rx);
+          }
+          TU_ASSERT(tu_edpt_stream_read_xfer(rhport, stream_rx) > 0, 0); // prepare for incoming data
+        }
+      }
 
-  return drv_len;
+      p_desc = tu_desc_next(p_desc);
+    }
+  }
+
+  return (uint16_t)(p_desc - (const uint8_t *)itf_desc);
 }
 
 // Invoked when a control transfer occurred on an interface of this class
@@ -449,7 +403,7 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
   }
   TU_VERIFY(itf < CFG_TUD_CDC);
 
-  switch (request->bRequest) { //-V2520 //-V2659
+  switch (request->bRequest) {
     case CDC_REQUEST_SET_LINE_CODING:
       if (stage == CONTROL_STAGE_SETUP) {
         TU_LOG_DRV("  Set Line Coding\r\n");
@@ -484,15 +438,13 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
 
         // If enabled: fifo overwriting is disabled if DTR bit is set and vice versa
         if (_cdcd_cfg.tx_overwritabe_if_not_connected) {
-          tu_fifo_set_overwritable(&p_cdc->tx_ff, !dtr);
+          tu_fifo_set_overwritable(&p_cdc->stream.tx.ff, !dtr);
         } else {
-          tu_fifo_set_overwritable(&p_cdc->tx_ff, false);
+          tu_fifo_set_overwritable(&p_cdc->stream.tx.ff, false);
         }
 
         TU_LOG_DRV("  Set Control Line State: DTR = %d, RTS = %d\r\n", dtr, rts);
-
-        // Invoke callback
-        tud_cdc_line_state_cb(itf, dtr, rts);
+        tud_cdc_line_state_cb(itf, dtr, rts); // invoke callback
       } else {
         // nothing to do
       }
@@ -507,7 +459,6 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
       } else {
         // nothing to do
       }
-
       break;
 
     default:
@@ -518,58 +469,45 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
 }
 
 bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes) {
-  (void) result;
+  (void)result;
 
-  uint8_t itf;
-  cdcd_interface_t* p_cdc;
-
-  // Identify which interface to use
-  for (itf = 0; itf < CFG_TUD_CDC; itf++) {
-    p_cdc = &_cdcd_itf[itf];
-    if ((ep_addr == p_cdc->ep_out) || (ep_addr == p_cdc->ep_in) || (ep_addr == p_cdc->ep_notify)) {
-      break;
-    }
-  }
+  uint8_t itf = find_cdc_itf(ep_addr);
   TU_ASSERT(itf < CFG_TUD_CDC);
-  cdcd_epbuf_t* p_epbuf = &_cdcd_epbuf[itf];
+  cdcd_interface_t *p_cdc     = &_cdcd_itf[itf];
+  tu_edpt_stream_t *stream_rx = &p_cdc->stream.rx;
+  tu_edpt_stream_t *stream_tx = &p_cdc->stream.tx;
 
-  // Received new data
-  if (ep_addr == p_cdc->ep_out) {
-    tu_fifo_write_n(&p_cdc->rx_ff, p_epbuf->epout, (uint16_t) xferred_bytes);
+  // Received new data, move to fifo
+  if (ep_addr == stream_rx->ep_addr) {
+    tu_edpt_stream_read_xfer_complete(stream_rx, xferred_bytes);
 
-    // Check for wanted char and invoke callback if needed
-    if (((signed char) p_cdc->wanted_char) != -1) {
+    // Check for wanted char and invoke wanted callback (multiple times if multiple wanted received)
+    if (((signed char)p_cdc->wanted_char) != -1) {
       for (uint32_t i = 0; i < xferred_bytes; i++) {
-        if ((p_cdc->wanted_char == (char) p_epbuf->epout[i]) && !tu_fifo_empty(&p_cdc->rx_ff)) {
+        if ((p_cdc->wanted_char == (char)stream_rx->ep_buf[i]) && !tu_edpt_stream_empty(stream_rx)) {
           tud_cdc_rx_wanted_cb(itf, p_cdc->wanted_char);
         }
       }
     }
 
-    // invoke receive callback (if there is still data)
-    if (!tu_fifo_empty(&p_cdc->rx_ff)) {
+    // invoke receive callback if there is still data
+    if (!tu_edpt_stream_empty(stream_rx)) {
       tud_cdc_rx_cb(itf);
     }
 
-    // prepare for OUT transaction
-    _prep_out_transaction(itf);
+    tu_edpt_stream_read_xfer(rhport, stream_rx); // prepare for more data
   }
 
   // Data sent to host, we continue to fetch from tx fifo to send.
   // Note: This will cause incorrect baudrate set in line coding.
   //       Though maybe the baudrate is not really important !!!
-  if (ep_addr == p_cdc->ep_in) {
+  if (ep_addr == stream_tx->ep_addr) {
     // invoke transmit callback to possibly refill tx fifo
     tud_cdc_tx_complete_cb(itf);
 
-    if (0 == tud_cdc_n_write_flush(itf)) {
-      // If there is no data left, a ZLP should be sent if
-      // xferred_bytes is multiple of EP Packet size and not zero
-      if (0 == tu_fifo_count(&p_cdc->tx_ff) && xferred_bytes > 0 && (0 == (xferred_bytes & (BULK_PACKET_SIZE - 1)))) {
-        if (usbd_edpt_claim(rhport, p_cdc->ep_in)) {
-          TU_ASSERT(usbd_edpt_xfer(rhport, p_cdc->ep_in, NULL, 0, false));
-        }
-      }
+    if (0 == tu_edpt_stream_write_xfer(rhport, stream_tx)) {
+      // If there is no data left, a ZLP should be sent if needed
+      tu_edpt_stream_write_zlp_if_needed(rhport, stream_tx, xferred_bytes);
     }
   }
 
diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index 7fdf0a7b9..35717ddf6 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -298,6 +298,7 @@ TU_VERIFY_STATIC(TU_ARRAY_SIZE(serial_drivers) == SERIAL_DRIVER_COUNT, "Serial d
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
+static bool open_ep_stream_pair(cdch_interface_t *p_cdc, const tusb_desc_endpoint_t *desc_ep);
 
 TU_ATTR_ALWAYS_INLINE static inline cdch_interface_t * get_itf(uint8_t idx) {
   TU_ASSERT(idx < CFG_TUH_CDC, NULL);
@@ -364,7 +365,7 @@ static cdch_interface_t* get_itf_by_xfer(const tuh_xfer_t * xfer) {
         #endif
 
         default:
-          break;
+          break; // unknown driver
       }
     }
   }
@@ -389,8 +390,6 @@ static cdch_interface_t * make_new_itf(uint8_t daddr, tusb_desc_interface_t cons
   return NULL;
 }
 
-static bool open_ep_stream_pair(cdch_interface_t * p_cdc , tusb_desc_endpoint_t const *desc_ep);
-
 //--------------------------------------------------------------------+
 // Weak stubs: invoked if no strong implementation is available
 //--------------------------------------------------------------------+
@@ -519,7 +518,7 @@ bool tuh_cdc_read_clear (uint8_t idx) {
   TU_VERIFY(p_cdc);
 
   bool ret = tu_edpt_stream_clear(&p_cdc->stream.rx);
-  tu_edpt_stream_read_xfer(p_cdc->daddr, &p_cdc->stream.rx);
+  (void)tu_edpt_stream_read_xfer(p_cdc->daddr, &p_cdc->stream.rx);
   return ret;
 }
 
@@ -648,13 +647,10 @@ bool cdch_init(void) {
   for (size_t i = 0; i < CFG_TUH_CDC; i++) {
     cdch_interface_t *p_cdc = &cdch_data[i];
     cdch_epbuf_t *epbuf = &cdch_epbuf[i];
-    tu_edpt_stream_init(&p_cdc->stream.tx, true, true, false,
-                        p_cdc->stream.tx_ff_buf, CFG_TUH_CDC_TX_BUFSIZE,
-                        epbuf->tx, CFG_TUH_CDC_TX_EPSIZE);
-
-    tu_edpt_stream_init(&p_cdc->stream.rx, true, false, false,
-                        p_cdc->stream.rx_ff_buf, CFG_TUH_CDC_RX_BUFSIZE,
-                        epbuf->rx, CFG_TUH_CDC_RX_EPSIZE);
+    TU_ASSERT(tu_edpt_stream_init(&p_cdc->stream.tx, true, true, false, p_cdc->stream.tx_ff_buf, CFG_TUH_CDC_TX_BUFSIZE,
+                                  epbuf->tx, CFG_TUH_CDC_TX_EPSIZE));
+    TU_ASSERT(tu_edpt_stream_init(&p_cdc->stream.rx, true, false, false, p_cdc->stream.rx_ff_buf,
+                                  CFG_TUH_CDC_RX_BUFSIZE, epbuf->rx, CFG_TUH_CDC_RX_EPSIZE));
   }
 
   return true;
@@ -663,8 +659,8 @@ bool cdch_init(void) {
 bool cdch_deinit(void) {
   for (size_t i = 0; i < CFG_TUH_CDC; i++) {
     cdch_interface_t *p_cdc = &cdch_data[i];
-    tu_edpt_stream_deinit(&p_cdc->stream.tx);
-    tu_edpt_stream_deinit(&p_cdc->stream.rx);
+    (void)tu_edpt_stream_deinit(&p_cdc->stream.tx);
+    (void)tu_edpt_stream_deinit(&p_cdc->stream.rx);
   }
   return true;
 }
@@ -674,11 +670,9 @@ void cdch_close(uint8_t daddr) {
     cdch_interface_t *p_cdc = &cdch_data[idx];
     if (p_cdc->daddr == daddr) {
       TU_LOG_CDC(p_cdc, "close");
+      tuh_cdc_umount_cb(idx); // invoke callback
 
-      // Invoke application callback
-      tuh_cdc_umount_cb(idx);
-
-      p_cdc->daddr = 0;
+      p_cdc->daddr            = 0;
       p_cdc->bInterfaceNumber = 0;
       p_cdc->mounted = false;
       tu_edpt_stream_close(&p_cdc->stream.tx);
@@ -696,13 +690,12 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
   TU_ASSERT(p_cdc);
 
   if (ep_addr == p_cdc->stream.tx.ep_addr) {
-    // invoke tx complete callback to possibly refill tx fifo
-    tuh_cdc_tx_complete_cb(idx);
+    tuh_cdc_tx_complete_cb(idx); // invoke transmit complete callback
 
     if (0 == tu_edpt_stream_write_xfer(daddr, &p_cdc->stream.tx)) {
       // If there is no data left, a ZLP should be sent if:
       // - xferred_bytes is multiple of EP Packet size and not zero
-      tu_edpt_stream_write_zlp_if_needed(daddr, &p_cdc->stream.tx, xferred_bytes);
+      (void)tu_edpt_stream_write_zlp_if_needed(daddr, &p_cdc->stream.tx, xferred_bytes);
     }
   } else if (ep_addr == p_cdc->stream.rx.ep_addr) {
     #if CFG_TUH_CDC_FTDI
@@ -718,7 +711,6 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
     #endif
     {
       tu_edpt_stream_read_xfer_complete(&p_cdc->stream.rx, xferred_bytes);
-
       tuh_cdc_rx_cb(idx); // invoke receive callback
     }
 
@@ -727,7 +719,7 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
   } else if (ep_addr == p_cdc->ep_notif) {
     // TODO handle notification endpoint
   } else {
-    TU_ASSERT(false);
+    return false;
   }
 
   return true;
@@ -736,20 +728,17 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
 //--------------------------------------------------------------------+
 // Enumeration
 //--------------------------------------------------------------------+
-
 static bool open_ep_stream_pair(cdch_interface_t *p_cdc, tusb_desc_endpoint_t const *desc_ep) {
   for (size_t i = 0; i < 2; i++) {
     TU_ASSERT(TUSB_DESC_ENDPOINT == desc_ep->bDescriptorType &&
               TUSB_XFER_BULK == desc_ep->bmAttributes.xfer);
     TU_ASSERT(tuh_edpt_open(p_cdc->daddr, desc_ep));
+    tu_edpt_stream_t *stream =
+      (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN) ? &p_cdc->stream.rx : &p_cdc->stream.tx;
+    tu_edpt_stream_open(stream, desc_ep);
+    tu_edpt_stream_clear(stream);
 
-    if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN) {
-      tu_edpt_stream_open(&p_cdc->stream.rx, desc_ep);
-    } else {
-      tu_edpt_stream_open(&p_cdc->stream.tx, desc_ep);
-    }
-
-    desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(desc_ep);
+    desc_ep = (const tusb_desc_endpoint_t *)tu_desc_next(desc_ep);
   }
 
   return true;
@@ -832,6 +821,7 @@ static void cdch_process_set_config(tuh_xfer_t *xfer) {
   }
 }
 
+// return false if there is no active transfer
 static bool set_line_state_on_enum(cdch_interface_t *p_cdc, tuh_xfer_t *xfer) {
   enum {
     ENUM_SET_LINE_CODING = 0,
diff --git a/src/class/dfu/dfu_device.c b/src/class/dfu/dfu_device.c
index 0d2b63b57..d3cc53918 100644
--- a/src/class/dfu/dfu_device.c
+++ b/src/class/dfu/dfu_device.c
@@ -50,21 +50,17 @@
 typedef struct {
   uint8_t attrs;
   uint8_t alt;
+  uint8_t state;
+  uint8_t status;
 
-  dfu_state_t state;
-  dfu_status_t status;
-
-  bool flashing_in_progress;
+  bool     flashing_in_progress;
   uint16_t block;
   uint16_t length;
 } dfu_state_ctx_t;
 
-// Only a single dfu state is allowed
 static dfu_state_ctx_t _dfu_ctx;
 
-CFG_TUD_MEM_SECTION static struct {
-  TUD_EPBUF_DEF(transfer_buf, CFG_TUD_DFU_XFER_BUFSIZE);
-} _dfu_epbuf;
+TU_ATTR_ALIGNED(4) uint8_t _transfer_buf[CFG_TUD_DFU_XFER_BUFSIZE];
 
 static void reset_state(void) {
   _dfu_ctx.state = DFU_IDLE;
@@ -253,6 +249,8 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
           tud_control_status(rhport, request);
         } else if (stage == CONTROL_STAGE_ACK) {
           tud_dfu_detach_cb();
+        } else {
+          // nothing to do
         }
         break;
 
@@ -275,6 +273,8 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
           tud_control_status(rhport, request);
         } else if (stage == CONTROL_STAGE_ACK) {
           tud_dfu_abort_cb(_dfu_ctx.alt);
+        } else {
+          // nothing to do
         }
         break;
 
@@ -283,10 +283,10 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
           TU_VERIFY(_dfu_ctx.attrs & DFU_ATTR_CAN_UPLOAD);
           TU_VERIFY(request->wLength <= CFG_TUD_DFU_XFER_BUFSIZE);
 
-          const uint16_t xfer_len = tud_dfu_upload_cb(_dfu_ctx.alt, request->wValue, _dfu_epbuf.transfer_buf,
+          const uint16_t xfer_len = tud_dfu_upload_cb(_dfu_ctx.alt, request->wValue, _transfer_buf,
                                                       request->wLength);
 
-          return tud_control_xfer(rhport, request, _dfu_epbuf.transfer_buf, xfer_len);
+          return tud_control_xfer(rhport, request, _transfer_buf, xfer_len);
         }
         break;
 
@@ -303,10 +303,10 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
           _dfu_ctx.block = request->wValue;
           _dfu_ctx.length = request->wLength;
 
-          if (request->wLength) {
+          if (request->wLength > 0) {
             // Download with payload -> transition to DOWNLOAD SYNC
             _dfu_ctx.state = DFU_DNLOAD_SYNC;
-            return tud_control_xfer(rhport, request, _dfu_epbuf.transfer_buf, request->wLength);
+            return tud_control_xfer(rhport, request, _transfer_buf, request->wLength);
           } else {
             // Download is complete -> transition to MANIFEST SYNC
             _dfu_ctx.state = DFU_MANIFEST_SYNC;
@@ -352,6 +352,8 @@ void tud_dfu_finish_flashing(uint8_t status) {
       _dfu_ctx.state = (_dfu_ctx.attrs & DFU_ATTR_MANIFESTATION_TOLERANT)
                          ? DFU_MANIFEST_SYNC
                          : DFU_MANIFEST_WAIT_RESET;
+    } else {
+      // nothing to do
     }
   } else {
     // failed while flashing, move to dfuError
@@ -378,10 +380,12 @@ static bool process_download_get_status(uint8_t rhport, uint8_t stage, const tus
   } else if (stage == CONTROL_STAGE_ACK) {
     if (_dfu_ctx.flashing_in_progress) {
       _dfu_ctx.state = DFU_DNBUSY;
-      tud_dfu_download_cb(_dfu_ctx.alt, _dfu_ctx.block, _dfu_epbuf.transfer_buf, _dfu_ctx.length);
+      tud_dfu_download_cb(_dfu_ctx.alt, _dfu_ctx.block, _transfer_buf, _dfu_ctx.length);
     } else {
       _dfu_ctx.state = DFU_DNLOAD_IDLE;
     }
+  } else {
+    // nothing to do
   }
 
   return true;
@@ -409,6 +413,8 @@ static bool process_manifest_get_status(uint8_t rhport, uint8_t stage, const tus
     } else {
       _dfu_ctx.state = DFU_IDLE;
     }
+  } else {
+    // nothing to do
   }
 
   return true;
diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index c4b4925d6..b20903d68 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -37,12 +37,18 @@
 #include "midi_device.h"
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_midi_rx_cb(uint8_t itf) {
+  (void)itf;
+}
+
+//--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
 typedef struct {
+  uint8_t rhport;
   uint8_t itf_num;
-  uint8_t ep_in;
-  uint8_t ep_out;
 
   // For Stream read()/write() API
   // Messages are always 4 bytes long, queue them for reading and writing so the
@@ -51,134 +57,97 @@ typedef struct {
   midi_driver_stream_t stream_read;
 
   /*------------- From this point, data is not cleared by bus reset -------------*/
-  // FIFO
-  tu_fifo_t rx_ff;
-  tu_fifo_t tx_ff;
-  uint8_t rx_ff_buf[CFG_TUD_MIDI_RX_BUFSIZE];
-  uint8_t tx_ff_buf[CFG_TUD_MIDI_TX_BUFSIZE];
+  // Endpoint stream
+  struct {
+    tu_edpt_stream_t tx;
+    tu_edpt_stream_t rx;
 
-  #if CFG_FIFO_MUTEX
-  osal_mutex_def_t rx_ff_mutex;
-  osal_mutex_def_t tx_ff_mutex;
-  #endif
+    uint8_t rx_ff_buf[CFG_TUD_MIDI_RX_BUFSIZE];
+    uint8_t tx_ff_buf[CFG_TUD_MIDI_TX_BUFSIZE];
+  } ep_stream;
 } midid_interface_t;
 
-#define ITF_MEM_RESET_SIZE   offsetof(midid_interface_t, rx_ff)
+#define ITF_MEM_RESET_SIZE offsetof(midid_interface_t, ep_stream)
+
+static midid_interface_t _midid_itf[CFG_TUD_MIDI];
 
 // Endpoint Transfer buffer
-CFG_TUD_MEM_SECTION static struct {
+typedef struct {
   TUD_EPBUF_DEF(epin, CFG_TUD_MIDI_EP_BUFSIZE);
   TUD_EPBUF_DEF(epout, CFG_TUD_MIDI_EP_BUFSIZE);
-} _midid_epbuf[CFG_TUD_MIDI];
+} midid_epbuf_t;
+
+CFG_TUD_MEM_SECTION static midid_epbuf_t _midid_epbuf[CFG_TUD_MIDI];
 
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
-static midid_interface_t _midid_itf[CFG_TUD_MIDI];
-
 bool tud_midi_n_mounted (uint8_t itf) {
-  midid_interface_t* midi = &_midid_itf[itf];
-  return midi->ep_in && midi->ep_out;
-}
-
-static void _prep_out_transaction(uint8_t idx) {
-  const uint8_t rhport = 0;
-  midid_interface_t* p_midi = &_midid_itf[idx];
-  uint16_t available = tu_fifo_remaining(&p_midi->rx_ff);
-
-  // Prepare for incoming data but only allow what we can store in the ring buffer.
-  // TODO Actually we can still carry out the transfer, keeping count of received bytes
-  // and slowly move it to the FIFO when read().
-  // This pre-check reduces endpoint claiming
-  TU_VERIFY(available >= CFG_TUD_MIDI_EP_BUFSIZE, );
-
-  // claim endpoint
-  TU_VERIFY(usbd_edpt_claim(rhport, p_midi->ep_out), );
-
-  // fifo can be changed before endpoint is claimed
-  available = tu_fifo_remaining(&p_midi->rx_ff);
-
-  if ( available >= CFG_TUD_MIDI_EP_BUFSIZE )  {
-    usbd_edpt_xfer(rhport, p_midi->ep_out, _midid_epbuf[idx].epout, CFG_TUD_MIDI_EP_BUFSIZE, false);
-  }else
-  {
-    // Release endpoint since we don't make any transfer
-    usbd_edpt_release(rhport, p_midi->ep_out);
-  }
-}
-
+  midid_interface_t *p_midi = &_midid_itf[itf];
 
-//--------------------------------------------------------------------+
-// Weak stubs: invoked if no strong implementation is available
-//--------------------------------------------------------------------+
-TU_ATTR_WEAK void tud_midi_rx_cb(uint8_t itf) {
-  (void) itf;
+  const bool tx_opened = tu_edpt_stream_is_opened(&p_midi->ep_stream.tx);
+  const bool rx_opened = tu_edpt_stream_is_opened(&p_midi->ep_stream.rx);
+  return tx_opened && rx_opened;
 }
 
 //--------------------------------------------------------------------+
 // READ API
 //--------------------------------------------------------------------+
-uint32_t tud_midi_n_available(uint8_t itf, uint8_t cable_num)
-{
+uint32_t tud_midi_n_available(uint8_t itf, uint8_t cable_num) {
   (void) cable_num;
-
-  midid_interface_t* midi = &_midid_itf[itf];
-  const midi_driver_stream_t* stream = &midi->stream_read;
+  const midid_interface_t    *p_midi = &_midid_itf[itf];
+  const midi_driver_stream_t *stream = &p_midi->stream_read;
+  const tu_edpt_stream_t     *ep_str = &p_midi->ep_stream.rx;
 
   // when using with packet API stream total & index are both zero
-  return tu_fifo_count(&midi->rx_ff) + (uint8_t) (stream->total - stream->index);
+  return tu_edpt_stream_read_available(ep_str) + (uint8_t)(stream->total - stream->index);
 }
 
-uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void* buffer, uint32_t bufsize)
-{
+uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void *buffer, uint32_t bufsize) {
   (void) cable_num;
-  TU_VERIFY(bufsize, 0);
-
-  uint8_t* buf8 = (uint8_t*) buffer;
+  TU_VERIFY(buffer != NULL && bufsize > 0, 0);
 
-  midid_interface_t* midi = &_midid_itf[itf];
-  midi_driver_stream_t* stream = &midi->stream_read;
+  uint8_t              *buf8   = (uint8_t *)buffer;
+  midid_interface_t    *p_midi = &_midid_itf[itf];
+  midi_driver_stream_t *stream = &p_midi->stream_read;
 
   uint32_t total_read = 0;
-  while( bufsize )
-  {
+  while (bufsize > 0) {
     // Get new packet from fifo, then set packet expected bytes
-    if ( stream->total == 0 )
-    {
-      // return if there is no more data from fifo
-      if ( !tud_midi_n_packet_read(itf, stream->buffer) ) return total_read;
+    if (stream->total == 0) {
+      if (!tud_midi_n_packet_read(itf, stream->buffer)) {
+        return total_read; // return if there is no more data from fifo
+      }
 
-      uint8_t const code_index = stream->buffer[0] & 0x0f;
+      const uint8_t code_index = stream->buffer[0] & 0x0f;
 
       // MIDI 1.0 Table 4-1: Code Index Number Classifications
-      switch(code_index)
-      {
+      switch (code_index) {
         case MIDI_CIN_MISC:
         case MIDI_CIN_CABLE_EVENT:
           // These are reserved and unused, possibly issue somewhere, skip this packet
           return 0;
-        break;
 
         case MIDI_CIN_SYSEX_END_1BYTE:
         case MIDI_CIN_1BYTE_DATA:
           stream->total = 1;
-        break;
+          break;
 
         case MIDI_CIN_SYSCOM_2BYTE     :
         case MIDI_CIN_SYSEX_END_2BYTE  :
         case MIDI_CIN_PROGRAM_CHANGE   :
         case MIDI_CIN_CHANNEL_PRESSURE :
           stream->total = 2;
-        break;
+          break;
 
         default:
           stream->total = 3;
-        break;
+          break;
       }
     }
 
     // Copy data up to bufsize
-    uint8_t const count = (uint8_t) tu_min32(stream->total - stream->index, bufsize);
+    const uint8_t count = (uint8_t)tu_min32((uint32_t)(stream->total - stream->index), bufsize);
 
     // Skip the header (1st byte) in the buffer
     TU_VERIFY(0 == tu_memcpy_s(buf8, bufsize, stream->buffer + 1 + stream->index, count));
@@ -189,8 +158,7 @@ uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void* buffer, ui
     bufsize -= count;
 
     // complete current event packet, reset stream
-    if ( stream->total == stream->index )
-    {
+    if (stream->total == stream->index) {
       stream->index = 0;
       stream->total = 0;
     }
@@ -199,150 +167,107 @@ uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void* buffer, ui
   return total_read;
 }
 
-bool tud_midi_n_packet_read (uint8_t itf, uint8_t packet[4])
-{
-  midid_interface_t* midi = &_midid_itf[itf];
-  TU_VERIFY(midi->ep_out);
+bool tud_midi_n_packet_read(uint8_t itf, uint8_t packet[4]) {
+  midid_interface_t *p_midi = &_midid_itf[itf];
+  tu_edpt_stream_t  *ep_str = &p_midi->ep_stream.rx;
+  TU_VERIFY(tu_edpt_stream_is_opened(ep_str));
+  return 4 == tu_edpt_stream_read(p_midi->rhport, ep_str, packet, 4);
+}
+
+uint32_t tud_midi_n_packet_read_n(uint8_t itf, uint8_t packets[], uint32_t max_packets) {
+  midid_interface_t *p_midi = &_midid_itf[itf];
+  tu_edpt_stream_t  *ep_str = &p_midi->ep_stream.rx;
+  TU_VERIFY(tu_edpt_stream_is_opened(ep_str), 0);
 
-  const uint32_t num_read = tu_fifo_read_n(&midi->rx_ff, packet, 4);
-  _prep_out_transaction(itf);
-  return (num_read == 4);
+  const uint32_t num_read = tu_edpt_stream_read(p_midi->rhport, ep_str, packets, 4u * max_packets);
+  return num_read >> 2u;
 }
 
 //--------------------------------------------------------------------+
 // WRITE API
 //--------------------------------------------------------------------+
-
-static uint32_t write_flush(uint8_t idx) {
-  midid_interface_t* midi = &_midid_itf[idx];
-
-  if (!tu_fifo_count(&midi->tx_ff)) {
-    return 0; // No data to send
-  }
-
-  const uint8_t rhport = 0;
-
-  // skip if previous transfer not complete
-  TU_VERIFY( usbd_edpt_claim(rhport, midi->ep_in), 0 );
-
-  uint16_t count = tu_fifo_read_n(&midi->tx_ff, _midid_epbuf[idx].epin, CFG_TUD_MIDI_EP_BUFSIZE);
-
-  if (count) {
-    TU_ASSERT( usbd_edpt_xfer(rhport, midi->ep_in, _midid_epbuf[idx].epin, count, false), 0 );
-    return count;
-  }else {
-    // Release endpoint since we don't make any transfer
-    usbd_edpt_release(rhport, midi->ep_in);
-    return 0;
-  }
-}
-
-uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, const uint8_t* buffer, uint32_t bufsize)
-{
-  midid_interface_t* midi = &_midid_itf[itf];
-  TU_VERIFY(midi->ep_in, 0);
-
-  midi_driver_stream_t* stream = &midi->stream_write;
+uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, const uint8_t *buffer, uint32_t bufsize) {
+  midid_interface_t *p_midi = &_midid_itf[itf];
+  midi_driver_stream_t *stream = &p_midi->stream_write;
+  tu_edpt_stream_t  *ep_str = &p_midi->ep_stream.tx;
+  TU_VERIFY(tu_edpt_stream_is_opened(ep_str), 0);
 
   uint32_t i = 0;
-  while ( (i < bufsize) && (tu_fifo_remaining(&midi->tx_ff) >= 4) )
-  {
+  while (i < bufsize) {
+    if (tu_edpt_stream_write_available(p_midi->rhport, ep_str) < 4) {
+      break;
+    }
+
     const uint8_t data = buffer[i];
     i++;
 
-    if ( stream->index == 0 )
-    {
+    if (stream->index == 0) {
       //------------- New event packet -------------//
       const uint8_t msg = data >> 4;
 
-      stream->index = 2;
+      stream->index     = 2;
       stream->buffer[1] = data;
 
       // Check to see if we're still in a SysEx transmit.
-      if ( ((stream->buffer[0]) & 0xF) == MIDI_CIN_SYSEX_START )
-      {
-        if ( data == MIDI_STATUS_SYSEX_END )
-        {
-          stream->buffer[0] = (uint8_t) ((cable_num << 4) | MIDI_CIN_SYSEX_END_1BYTE);
-          stream->total = 2;
-        }
-        else
-        {
+      if (((stream->buffer[0]) & 0xF) == MIDI_CIN_SYSEX_START) {
+        if (data == MIDI_STATUS_SYSEX_END) {
+          stream->buffer[0] = (uint8_t)((cable_num << 4) | MIDI_CIN_SYSEX_END_1BYTE);
+          stream->total     = 2;
+        } else {
           stream->total = 4;
         }
-      }
-      else if ( (msg >= 0x8 && msg <= 0xB) || msg == 0xE )
-      {
+      } else if ((msg >= 0x8 && msg <= 0xB) || msg == 0xE) {
         // Channel Voice Messages
-        stream->buffer[0] = (uint8_t) ((cable_num << 4) | msg);
-        stream->total = 4;
-      }
-      else if ( msg == 0xC || msg == 0xD)
-      {
+        stream->buffer[0] = (uint8_t)((cable_num << 4) | msg);
+        stream->total     = 4;
+      } else if (msg == 0xC || msg == 0xD) {
         // Channel Voice Messages, two-byte variants (Program Change and Channel Pressure)
-        stream->buffer[0] = (uint8_t) ((cable_num << 4) | msg);
-        stream->total = 3;
-      }
-      else if ( msg == 0xf )
-      {
+        stream->buffer[0] = (uint8_t)((cable_num << 4) | msg);
+        stream->total     = 3;
+      } else if (msg == 0xf) {
         // System message
-        if ( data == MIDI_STATUS_SYSEX_START )
-        {
+        if (data == MIDI_STATUS_SYSEX_START) {
           stream->buffer[0] = MIDI_CIN_SYSEX_START;
-          stream->total = 4;
-        }
-        else if ( data == MIDI_STATUS_SYSCOM_TIME_CODE_QUARTER_FRAME || data == MIDI_STATUS_SYSCOM_SONG_SELECT )
-        {
+          stream->total     = 4;
+        } else if (data == MIDI_STATUS_SYSCOM_TIME_CODE_QUARTER_FRAME || data == MIDI_STATUS_SYSCOM_SONG_SELECT) {
           stream->buffer[0] = MIDI_CIN_SYSCOM_2BYTE;
-          stream->total = 3;
-        }
-        else if ( data == MIDI_STATUS_SYSCOM_SONG_POSITION_POINTER )
-        {
+          stream->total     = 3;
+        } else if (data == MIDI_STATUS_SYSCOM_SONG_POSITION_POINTER) {
           stream->buffer[0] = MIDI_CIN_SYSCOM_3BYTE;
-          stream->total = 4;
-        }
-        else
-        {
+          stream->total     = 4;
+        } else {
           stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
-          stream->total = 2;
+          stream->total     = 2;
         }
         stream->buffer[0] |= (uint8_t)(cable_num << 4);
-      }
-      else
-      {
+      } else {
         // Pack individual bytes if we don't support packing them into words.
-        stream->buffer[0] = (uint8_t) (cable_num << 4 | 0xf);
+        stream->buffer[0] = (uint8_t)(cable_num << 4 | 0xf);
         stream->buffer[2] = 0;
         stream->buffer[3] = 0;
-        stream->index = 2;
-        stream->total = 2;
+        stream->total     = 2; // index already set to 2
       }
-    }
-    else
-    {
+    } else {
       //------------- On-going (buffering) packet -------------//
-
       TU_ASSERT(stream->index < 4, i);
       stream->buffer[stream->index] = data;
       stream->index++;
 
       // See if this byte ends a SysEx.
-      if ( (stream->buffer[0] & 0xF) == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
-      {
-        stream->buffer[0] = (uint8_t) ((cable_num << 4) | (MIDI_CIN_SYSEX_START + (stream->index - 1)));
-        stream->total = stream->index;
+      if ((stream->buffer[0] & 0xF) == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END) {
+        stream->buffer[0] = (uint8_t)((cable_num << 4) | (MIDI_CIN_SYSEX_START + (stream->index - 1)));
+        stream->total     = stream->index;
       }
     }
 
     // Send out packet
-    if ( stream->index == stream->total )
-    {
+    if (stream->index == stream->total) {
       // zeroes unused bytes
       for (uint8_t idx = stream->total; idx < 4; idx++) {
         stream->buffer[idx] = 0;
       }
 
-      const uint16_t count = tu_fifo_write_n(&midi->tx_ff, stream->buffer, 4);
+      const uint32_t count = tu_edpt_stream_write(p_midi->rhport, ep_str, stream->buffer, 4);
 
       // complete current event packet, reset stream
       stream->index = stream->total = 0;
@@ -352,25 +277,37 @@ uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, const uint8_t*
     }
   }
 
-  write_flush(itf);
+  (void)tu_edpt_stream_write_xfer(p_midi->rhport, ep_str);
 
   return i;
 }
 
 bool tud_midi_n_packet_write (uint8_t itf, const uint8_t packet[4]) {
-  midid_interface_t* midi = &_midid_itf[itf];
-  TU_VERIFY(midi->ep_in);
+  midid_interface_t *p_midi = &_midid_itf[itf];
+  tu_edpt_stream_t  *ep_str = &p_midi->ep_stream.tx;
+  TU_VERIFY(tu_edpt_stream_is_opened(ep_str));
 
-  if (tu_fifo_remaining(&midi->tx_ff) < 4) {
-    return false;
-  }
-
-  tu_fifo_write_n(&midi->tx_ff, packet, 4);
-  write_flush(itf);
+  TU_VERIFY(tu_edpt_stream_write_available(p_midi->rhport, ep_str) >= 4);
+  TU_VERIFY(tu_edpt_stream_write(p_midi->rhport, ep_str, packet, 4) > 0);
+  (void)tu_edpt_stream_write_xfer(p_midi->rhport, ep_str);
 
   return true;
 }
 
+uint32_t tud_midi_n_packet_write_n(uint8_t itf, const uint8_t packets[], uint32_t n_packets) {
+  midid_interface_t *p_midi = &_midid_itf[itf];
+  tu_edpt_stream_t  *ep_str = &p_midi->ep_stream.tx;
+  TU_VERIFY(tu_edpt_stream_is_opened(ep_str), 0);
+
+  uint32_t n_bytes = tu_edpt_stream_write_available(p_midi->rhport, ep_str);
+  n_bytes          = tu_min32(tu_align4(n_bytes), n_packets << 2u);
+
+  const uint32_t n_write = tu_edpt_stream_write(p_midi->rhport, ep_str, packets, n_bytes);
+  (void)tu_edpt_stream_write_xfer(p_midi->rhport, ep_str);
+
+  return n_write >> 2u;
+}
+
 //--------------------------------------------------------------------+
 // USBD Driver API
 //--------------------------------------------------------------------+
@@ -378,72 +315,64 @@ void midid_init(void) {
   tu_memclr(_midid_itf, sizeof(_midid_itf));
 
   for (uint8_t i = 0; i < CFG_TUD_MIDI; i++) {
-    midid_interface_t* midi = &_midid_itf[i];
-
-    // config fifo
-    tu_fifo_config(&midi->rx_ff, midi->rx_ff_buf, CFG_TUD_MIDI_RX_BUFSIZE, 1, false); // true, true
-    tu_fifo_config(&midi->tx_ff, midi->tx_ff_buf, CFG_TUD_MIDI_TX_BUFSIZE, 1, false); // OBVS.
+    midid_interface_t *p_midi  = &_midid_itf[i];
+    midid_epbuf_t     *p_epbuf = &_midid_epbuf[i];
 
-    #if CFG_FIFO_MUTEX
-    osal_mutex_t mutex_rd = osal_mutex_create(&midi->rx_ff_mutex);
-    osal_mutex_t mutex_wr = osal_mutex_create(&midi->tx_ff_mutex);
-    TU_ASSERT(mutex_wr != NULL && mutex_wr != NULL, );
+    tu_edpt_stream_init(
+        &p_midi->ep_stream.rx, false, false, false, p_midi->ep_stream.rx_ff_buf, CFG_TUD_MIDI_RX_BUFSIZE,
+        p_epbuf->epout, CFG_TUD_MIDI_EP_BUFSIZE);
 
-    tu_fifo_config_mutex(&midi->rx_ff, NULL, mutex_rd);
-    tu_fifo_config_mutex(&midi->tx_ff, mutex_wr, NULL);
-    #endif
+    tu_edpt_stream_init(
+        &p_midi->ep_stream.tx, false, true, false, p_midi->ep_stream.tx_ff_buf, CFG_TUD_MIDI_TX_BUFSIZE, p_epbuf->epin,
+        CFG_TUD_MIDI_EP_BUFSIZE);
   }
 }
 
 bool midid_deinit(void) {
-  #if CFG_FIFO_MUTEX
-  for(uint8_t i=0; i<CFG_TUD_MIDI; i++) {
-    midid_interface_t* midi = &_midid_itf[i];
-    osal_mutex_t mutex_rd = midi->rx_ff.mutex_rd;
-    osal_mutex_t mutex_wr = midi->tx_ff.mutex_wr;
-
-    if (mutex_rd) {
-      osal_mutex_delete(mutex_rd);
-      tu_fifo_config_mutex(&midi->rx_ff, NULL, NULL);
-    }
-
-    if (mutex_wr) {
-      osal_mutex_delete(mutex_wr);
-      tu_fifo_config_mutex(&midi->tx_ff, NULL, NULL);
-    }
+  for (uint8_t i = 0; i < CFG_TUD_MIDI; i++) {
+    midid_interface_t *p_midi = &_midid_itf[i];
+    tu_edpt_stream_deinit(&p_midi->ep_stream.rx);
+    tu_edpt_stream_deinit(&p_midi->ep_stream.tx);
   }
-  #endif
-
   return true;
 }
 
-void midid_reset(uint8_t rhport)
-{
-  (void) rhport;
+void midid_reset(uint8_t rhport) {
+  (void)rhport;
+  for (uint8_t i = 0; i < CFG_TUD_MIDI; i++) {
+    midid_interface_t *p_midi = &_midid_itf[i];
+    tu_memclr(p_midi, ITF_MEM_RESET_SIZE);
+
+    tu_edpt_stream_clear(&p_midi->ep_stream.rx);
+    tu_edpt_stream_close(&p_midi->ep_stream.rx);
+
+    tu_edpt_stream_clear(&p_midi->ep_stream.tx);
+    tu_edpt_stream_close(&p_midi->ep_stream.tx);
+  }
+}
 
-  for(uint8_t i=0; i<CFG_TUD_MIDI; i++)
-  {
-    midid_interface_t* midi = &_midid_itf[i];
-    tu_memclr(midi, ITF_MEM_RESET_SIZE);
-    tu_fifo_clear(&midi->rx_ff);
-    tu_fifo_clear(&midi->tx_ff);
+TU_ATTR_ALWAYS_INLINE static inline uint8_t find_midi_itf(uint8_t ep_addr) {
+  for (uint8_t idx = 0; idx < CFG_TUD_MIDI; idx++) {
+    const midid_interface_t *p_midi = &_midid_itf[idx];
+    if (ep_addr == p_midi->ep_stream.rx.ep_addr || ep_addr == p_midi->ep_stream.tx.ep_addr) {
+      return idx;
+    }
   }
+  return TUSB_INDEX_INVALID_8;
 }
 
-uint16_t midid_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uint16_t max_len) {
-  uint16_t drv_len = 0;
-  uint8_t const * p_desc = (uint8_t const *)desc_itf;
+uint16_t midid_open(uint8_t rhport, const tusb_desc_interface_t *desc_itf, uint16_t max_len) {
+  const uint8_t *p_desc   = (const uint8_t *)desc_itf;
+  const uint8_t *desc_end = p_desc + max_len;
 
   // 1st Interface is Audio Control v1 (optional)
   if (TUSB_CLASS_AUDIO               == desc_itf->bInterfaceClass    &&
       AUDIO_SUBCLASS_CONTROL         == desc_itf->bInterfaceSubClass &&
       AUDIO_FUNC_PROTOCOL_CODE_UNDEF == desc_itf->bInterfaceProtocol) {
-    drv_len = tu_desc_len(desc_itf);
     p_desc = tu_desc_next(desc_itf);
     // Skip Class Specific descriptors
-    while (TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc) && drv_len <= max_len) {
-      drv_len += tu_desc_len(p_desc);
-      p_desc   = tu_desc_next(p_desc);
+    while (tu_desc_in_bounds(p_desc, desc_end) && TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc)) {
+      p_desc = tu_desc_next(p_desc);
     }
   }
 
@@ -451,59 +380,48 @@ uint16_t midid_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uint1
   TU_VERIFY(TUSB_DESC_INTERFACE == tu_desc_type(p_desc), 0);
   const tusb_desc_interface_t* desc_midi = (const tusb_desc_interface_t*) p_desc;
 
-  TU_VERIFY(TUSB_CLASS_AUDIO               == desc_midi->bInterfaceClass    &&
-            AUDIO_SUBCLASS_MIDI_STREAMING  == desc_midi->bInterfaceSubClass &&
-            AUDIO_FUNC_PROTOCOL_CODE_UNDEF == desc_midi->bInterfaceProtocol, 0);
+  TU_VERIFY(TUSB_CLASS_AUDIO == desc_midi->bInterfaceClass &&
+              AUDIO_SUBCLASS_MIDI_STREAMING == desc_midi->bInterfaceSubClass &&
+              AUDIO_FUNC_PROTOCOL_CODE_UNDEF == desc_midi->bInterfaceProtocol,
+            0);
 
-  // Find available interface
-  midid_interface_t * p_midi = NULL;
-  uint8_t idx;
-  for(idx=0; idx<CFG_TUD_MIDI; idx++) {
-    if ( _midid_itf[idx].ep_in == 0 && _midid_itf[idx].ep_out == 0 ) {
-      p_midi = &_midid_itf[idx];
-      break;
-    }
-  }
-  TU_ASSERT(p_midi);
+  uint8_t idx = find_midi_itf(0); // find unused interface
+  TU_ASSERT(idx < CFG_TUD_MIDI, 0);
+  midid_interface_t *p_midi = &_midid_itf[idx];
 
+  p_midi->rhport  = rhport;
   p_midi->itf_num = desc_midi->bInterfaceNumber;
   (void) p_midi->itf_num;
 
-  // next descriptor
-  drv_len += tu_desc_len(p_desc);
-  p_desc   = tu_desc_next(p_desc);
+  p_desc = tu_desc_next(p_desc);
 
   // Find and open endpoint descriptors
-  uint8_t found_endpoints = 0;
-  while ( (found_endpoints < desc_midi->bNumEndpoints) && (drv_len <= max_len)  )
-  {
-    if ( TUSB_DESC_ENDPOINT == tu_desc_type(p_desc) )
-    {
-      TU_ASSERT(usbd_edpt_open(rhport, (const tusb_desc_endpoint_t*) p_desc), 0);
-      uint8_t ep_addr = ((const tusb_desc_endpoint_t*) p_desc)->bEndpointAddress;
+  uint8_t found_ep = 0;
+  while ((found_ep < desc_midi->bNumEndpoints) && tu_desc_in_bounds(p_desc, desc_end)) {
+    if (TUSB_DESC_ENDPOINT == tu_desc_type(p_desc)) {
+      const tusb_desc_endpoint_t *desc_ep = (const tusb_desc_endpoint_t *)p_desc;
+      TU_ASSERT(usbd_edpt_open(rhport, desc_ep), 0);
+      const uint8_t ep_addr = ((const tusb_desc_endpoint_t *)p_desc)->bEndpointAddress;
 
-      if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN)
-      {
-        p_midi->ep_in = ep_addr;
+      if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN) {
+        tu_edpt_stream_t *stream_tx = &p_midi->ep_stream.tx;
+        tu_edpt_stream_open(stream_tx, desc_ep);
+        tu_edpt_stream_clear(stream_tx);
       } else {
-        p_midi->ep_out = ep_addr;
+        tu_edpt_stream_t *stream_rx = &p_midi->ep_stream.rx;
+        tu_edpt_stream_open(stream_rx, desc_ep);
+        tu_edpt_stream_clear(stream_rx);
+        TU_ASSERT(tu_edpt_stream_read_xfer(rhport, stream_rx) > 0, 0); // prepare to receive data
       }
 
-      // Class Specific MIDI Stream endpoint descriptor
-      drv_len += tu_desc_len(p_desc);
-      p_desc   = tu_desc_next(p_desc);
-
-      found_endpoints += 1;
+      p_desc = tu_desc_next(p_desc);                                   // skip CS Endpoint descriptor
+      found_ep++;
     }
 
-    drv_len += tu_desc_len(p_desc);
-    p_desc   = tu_desc_next(p_desc);
+    p_desc = tu_desc_next(p_desc);
   }
 
-  // Prepare for incoming data
-  _prep_out_transaction(idx);
-
-  return drv_len;
+  return (uint16_t)(p_desc - (const uint8_t *)desc_itf);
 }
 
 // Invoked when a control transfer occurred on an interface of this class
@@ -514,44 +432,31 @@ bool midid_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_req
   return false; // driver doesn't support any request yet
 }
 
-bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
-{
-  (void) result;
-  (void) rhport;
-
-  uint8_t idx;
-  midid_interface_t* p_midi;
+bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes) {
+  (void)result;
 
-  // Identify which interface to use
-  for (idx = 0; idx < CFG_TUD_MIDI; idx++) {
-    p_midi = &_midid_itf[idx];
-    if ((ep_addr == p_midi->ep_out) || (ep_addr == p_midi->ep_in)) {
-      break;
-    }
-  }
+  uint8_t idx = find_midi_itf(ep_addr);
   TU_ASSERT(idx < CFG_TUD_MIDI);
+  midid_interface_t *p_midi = &_midid_itf[idx];
 
-  // receive new data
-  if (ep_addr == p_midi->ep_out) {
-    tu_fifo_write_n(&p_midi->rx_ff, _midid_epbuf[idx].epout, (uint16_t)xferred_bytes);
+  tu_edpt_stream_t *ep_st_rx = &p_midi->ep_stream.rx;
+  tu_edpt_stream_t *ep_st_tx = &p_midi->ep_stream.tx;
 
-    // invoke receive callback if available
-    tud_midi_rx_cb(idx);
-
-    // prepare for next
-    // TODO for now ep_out is not used by public API therefore there is no race condition,
-    // and does not need to claim like ep_in
-    _prep_out_transaction(idx);
-  } else if (ep_addr == p_midi->ep_in) {
-    if (0 == write_flush(idx)) {
-      // If there is no data left, a ZLP should be sent if
-      // xferred_bytes is multiple of EP size and not zero
-      if (!tu_fifo_count(&p_midi->tx_ff) && xferred_bytes && (0 == (xferred_bytes % CFG_TUD_MIDI_EP_BUFSIZE))) {
-        if (usbd_edpt_claim(rhport, p_midi->ep_in)) {
-          usbd_edpt_xfer(rhport, p_midi->ep_in, NULL, 0, false);
-        }
-      }
+  if (ep_addr == ep_st_rx->ep_addr) {
+    // Received new data: put into stream's fifo
+    if (result == XFER_RESULT_SUCCESS) {
+      tu_edpt_stream_read_xfer_complete(ep_st_rx, xferred_bytes);
+      tud_midi_rx_cb(idx);                      // invoke callback
     }
+    tu_edpt_stream_read_xfer(rhport, ep_st_rx); // prepare for next data
+  } else if (ep_addr == ep_st_tx->ep_addr && result == XFER_RESULT_SUCCESS) {
+    // sent complete: try to send more if possible
+    if (0 == tu_edpt_stream_write_xfer(rhport, ep_st_tx)) {
+      // If there is no data left, a ZLP should be sent if needed
+      (void)tu_edpt_stream_write_zlp_if_needed(rhport, ep_st_tx, xferred_bytes);
+    }
+  } else {
+    return false;
   }
 
   return true;
diff --git a/src/class/midi/midi_device.h b/src/class/midi/midi_device.h
index d23516cec..ddbc2f9f0 100644
--- a/src/class/midi/midi_device.h
+++ b/src/class/midi/midi_device.h
@@ -36,21 +36,21 @@
 
 #if !defined(CFG_TUD_MIDI_EP_BUFSIZE) && defined(CFG_TUD_MIDI_EPSIZE)
   #warning CFG_TUD_MIDI_EPSIZE is renamed to CFG_TUD_MIDI_EP_BUFSIZE, please update to use the new name
-  #define CFG_TUD_MIDI_EP_BUFSIZE    CFG_TUD_MIDI_EPSIZE
+  #define CFG_TUD_MIDI_EP_BUFSIZE CFG_TUD_MIDI_EPSIZE
 #endif
 
 #ifndef CFG_TUD_MIDI_EP_BUFSIZE
-  #define CFG_TUD_MIDI_EP_BUFSIZE     (TUD_OPT_HIGH_SPEED ? 512 : 64)
+  #define CFG_TUD_MIDI_EP_BUFSIZE (TUD_OPT_HIGH_SPEED ? 512 : 64)
 #endif
 
 #ifdef __cplusplus
- extern "C" {
+extern "C" {
 #endif
 
-/** \addtogroup MIDI_Serial Serial
- *  @{
- *  \defgroup   MIDI_Serial_Device Device
- *  @{ */
+//--------------------------------------------------------------------+
+// Application Callback API (optional)
+//--------------------------------------------------------------------+
+void tud_midi_rx_cb(uint8_t itf);
 
 //--------------------------------------------------------------------+
 // Application API (Multiple Interfaces)
@@ -58,117 +58,77 @@
 //--------------------------------------------------------------------+
 
 // Check if midi interface is mounted
-bool     tud_midi_n_mounted      (uint8_t itf);
+bool tud_midi_n_mounted(uint8_t itf);
 
 // Get the number of bytes available for reading
-uint32_t tud_midi_n_available    (uint8_t itf, uint8_t cable_num);
-
-// Read byte stream              (legacy)
-uint32_t tud_midi_n_stream_read  (uint8_t itf, uint8_t cable_num, void* buffer, uint32_t bufsize);
-
-// Write byte Stream             (legacy)
-uint32_t tud_midi_n_stream_write (uint8_t itf, uint8_t cable_num, uint8_t const* buffer, uint32_t bufsize);
-
-// Read event packet             (4 bytes)
-bool     tud_midi_n_packet_read  (uint8_t itf, uint8_t packet[4]);
-
-// Write event packet            (4 bytes)
-bool     tud_midi_n_packet_write (uint8_t itf, uint8_t const packet[4]);
+uint32_t tud_midi_n_available(uint8_t itf, uint8_t cable_num);
 
-//--------------------------------------------------------------------+
-// Application API (Single Interface)
-//--------------------------------------------------------------------+
-static inline bool     tud_midi_mounted      (void);
-static inline uint32_t tud_midi_available    (void);
-
-static inline uint32_t tud_midi_stream_read  (void* buffer, uint32_t bufsize);
-static inline uint32_t tud_midi_stream_write (uint8_t cable_num, uint8_t const* buffer, uint32_t bufsize);
-
-static inline bool     tud_midi_packet_read  (uint8_t packet[4]);
-static inline bool     tud_midi_packet_write (uint8_t const packet[4]);
-
-//------------- Deprecated API name  -------------//
-// TODO remove after 0.10.0 release
-
-TU_ATTR_DEPRECATED("tud_midi_read() is renamed to tud_midi_stream_read()")
-static inline uint32_t tud_midi_read (void* buffer, uint32_t bufsize)
-{
-  return tud_midi_stream_read(buffer, bufsize);
-}
+// Read byte stream (legacy)
+uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void *buffer, uint32_t bufsize);
 
-TU_ATTR_DEPRECATED("tud_midi_write() is renamed to tud_midi_stream_write()")
-static inline uint32_t tud_midi_write(uint8_t cable_num, uint8_t const* buffer, uint32_t bufsize)
-{
-  return tud_midi_stream_write(cable_num, buffer, bufsize);
-}
+// Write byte Stream (legacy)
+uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, const uint8_t *buffer, uint32_t bufsize);
 
+// Read an event 4-byte packet
+bool tud_midi_n_packet_read(uint8_t itf, uint8_t packet[4]);
 
-TU_ATTR_DEPRECATED("tud_midi_send() is renamed to tud_midi_packet_write()")
-static inline bool tud_midi_send(uint8_t packet[4])
-{
-  return tud_midi_packet_write(packet);
-}
+// Read multiple event packets, return number of read packets
+uint32_t tud_midi_n_packet_read_n(uint8_t itf, uint8_t packets[], uint32_t max_packets);
 
-TU_ATTR_DEPRECATED("tud_midi_receive() is renamed to tud_midi_packet_read()")
-static inline bool tud_midi_receive(uint8_t packet[4])
-{
-  return tud_midi_packet_read(packet);
-}
+// Write an event 4-byte packet
+bool tud_midi_n_packet_write(uint8_t itf, const uint8_t packet[4]);
 
-//--------------------------------------------------------------------+
-// Application Callback API (optional)
-//--------------------------------------------------------------------+
-void tud_midi_rx_cb(uint8_t itf);
+// Write multiple event packets, return number of written packets
+uint32_t tud_midi_n_packet_write_n(uint8_t itf, const uint8_t packets[], uint32_t n_packets);
 
 //--------------------------------------------------------------------+
-// Inline Functions
+// Application API (Single Interface)
 //--------------------------------------------------------------------+
-
-static inline bool tud_midi_mounted (void)
-{
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi_mounted(void) {
   return tud_midi_n_mounted(0);
 }
 
-static inline uint32_t tud_midi_available (void)
-{
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_available(void) {
   return tud_midi_n_available(0, 0);
 }
 
-static inline uint32_t tud_midi_stream_read (void* buffer, uint32_t bufsize)
-{
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_stream_read(void *buffer, uint32_t bufsize) {
   return tud_midi_n_stream_read(0, 0, buffer, bufsize);
 }
 
-static inline uint32_t tud_midi_stream_write (uint8_t cable_num, uint8_t const* buffer, uint32_t bufsize)
-{
+TU_ATTR_ALWAYS_INLINE static inline uint32_t
+tud_midi_stream_write(uint8_t cable_num, const uint8_t *buffer, uint32_t bufsize) {
   return tud_midi_n_stream_write(0, cable_num, buffer, bufsize);
 }
 
-static inline bool tud_midi_packet_read (uint8_t packet[4])
-{
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi_packet_read(uint8_t packet[4]) {
   return tud_midi_n_packet_read(0, packet);
 }
 
-static inline bool tud_midi_packet_write (uint8_t const packet[4])
-{
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_packet_read_n(uint8_t packets[], uint32_t max_packets) {
+  return tud_midi_n_packet_read_n(0, packets, max_packets);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi_packet_write(const uint8_t packet[4]) {
   return tud_midi_n_packet_write(0, packet);
 }
 
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_packet_write_n(const uint8_t packets[], uint32_t n_packets) {
+  return tud_midi_n_packet_write_n(0, packets, n_packets);
+}
+
 //--------------------------------------------------------------------+
 // Internal Class Driver API
 //--------------------------------------------------------------------+
-void     midid_init            (void);
-bool     midid_deinit          (void);
-void     midid_reset           (uint8_t rhport);
-uint16_t midid_open            (uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len);
-bool     midid_control_xfer_cb (uint8_t rhport, uint8_t stage, tusb_control_request_t const * request);
-bool     midid_xfer_cb         (uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint32_t xferred_bytes);
+void     midid_init(void);
+bool     midid_deinit(void);
+void     midid_reset(uint8_t rhport);
+uint16_t midid_open(uint8_t rhport, const tusb_desc_interface_t *itf_desc, uint16_t max_len);
+bool     midid_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_request_t *request);
+bool     midid_xfer_cb(uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint32_t xferred_bytes);
 
 #ifdef __cplusplus
- }
+}
 #endif
 
-#endif /* TUSB_MIDI_DEVICE_H_ */
-
-/** @} */
-/** @} */
+#endif
diff --git a/src/class/midi/midi_host.c b/src/class/midi/midi_host.c
index 8b78fe945..07062875c 100644
--- a/src/class/midi/midi_host.c
+++ b/src/class/midi/midi_host.c
@@ -59,9 +59,6 @@ typedef struct {
   uint8_t iInterface;
   uint8_t itf_count;        // number of interface including Audio Control + MIDI streaming
 
-  uint8_t ep_in;          // IN endpoint address
-  uint8_t ep_out;         // OUT endpoint address
-
   uint8_t rx_cable_count;  // IN endpoint CS descriptor bNumEmbMIDIJack value
   uint8_t tx_cable_count;  // OUT endpoint CS descriptor bNumEmbMIDIJack value
 
@@ -147,8 +144,6 @@ void midih_close(uint8_t daddr) {
       TU_LOG_DRV("  MIDI close addr = %u index = %u\r\n", daddr, idx);
       tuh_midi_umount_cb(idx);
 
-      p_midi->ep_in = 0;
-      p_midi->ep_out = 0;
       p_midi->bInterfaceNumber = 0;
       p_midi->rx_cable_count = 0;
       p_midi->tx_cable_count = 0;
@@ -169,23 +164,25 @@ bool midih_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint
   const uint8_t idx = get_idx_by_ep_addr(dev_addr, ep_addr);
   TU_VERIFY(idx < CFG_TUH_MIDI);
   midih_interface_t *p_midi = &_midi_host[idx];
+  tu_edpt_stream_t  *ep_str_rx = &p_midi->ep_stream.rx;
+  tu_edpt_stream_t  *ep_str_tx = &p_midi->ep_stream.tx;
 
-  if (ep_addr == p_midi->ep_stream.rx.ep_addr) {
+  if (ep_addr == ep_str_rx->ep_addr) {
     // receive new data, put it into FIFO and invoke callback if available
     // Note: some devices send back all zero packets even if there is no data ready
-    if (xferred_bytes && !tu_mem_is_zero(p_midi->ep_stream.rx.ep_buf, xferred_bytes)) {
-      tu_edpt_stream_read_xfer_complete(&p_midi->ep_stream.rx, xferred_bytes);
+    if (xferred_bytes && !tu_mem_is_zero(ep_str_rx->ep_buf, xferred_bytes)) {
+      tu_edpt_stream_read_xfer_complete(ep_str_rx, xferred_bytes);
       tuh_midi_rx_cb(idx, xferred_bytes);
     }
 
-    tu_edpt_stream_read_xfer(dev_addr, &p_midi->ep_stream.rx); // prepare for next transfer
-  } else if (ep_addr == p_midi->ep_stream.tx.ep_addr) {
+    tu_edpt_stream_read_xfer(dev_addr, ep_str_rx); // prepare for next transfer
+  } else if (ep_addr == ep_str_tx->ep_addr) {
     tuh_midi_tx_cb(idx, xferred_bytes);
 
-    if (0 == tu_edpt_stream_write_xfer(dev_addr, &p_midi->ep_stream.tx)) {
+    if (0 == tu_edpt_stream_write_xfer(dev_addr, ep_str_tx)) {
       // If there is no data left, a ZLP should be sent if
       // xferred_bytes is multiple of EP size and not zero
-      tu_edpt_stream_write_zlp_if_needed(dev_addr, &p_midi->ep_stream.tx, xferred_bytes);
+      tu_edpt_stream_write_zlp_if_needed(dev_addr, ep_str_tx, xferred_bytes);
     }
   }
 
@@ -295,21 +292,20 @@ bool midih_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *d
         const midi_desc_cs_endpoint_t *p_csep = (const midi_desc_cs_endpoint_t *) p_desc;
 
         TU_LOG_DRV("  Endpoint and CS_Endpoint descriptor %02x\r\n", p_ep->bEndpointAddress);
+        tu_edpt_stream_t *ep_stream;
         if (tu_edpt_dir(p_ep->bEndpointAddress) == TUSB_DIR_OUT) {
-          p_midi->ep_out = p_ep->bEndpointAddress;
           p_midi->tx_cable_count = p_csep->bNumEmbMIDIJack;
           desc_cb.desc_epout = p_ep;
-
-          TU_ASSERT(tuh_edpt_open(dev_addr, p_ep));
-          tu_edpt_stream_open(&p_midi->ep_stream.tx, p_ep);
+          ep_stream              = &p_midi->ep_stream.tx;
         } else {
-          p_midi->ep_in = p_ep->bEndpointAddress;
           p_midi->rx_cable_count = p_csep->bNumEmbMIDIJack;
-          desc_cb.desc_epin = p_ep;
-
-          TU_ASSERT(tuh_edpt_open(dev_addr, p_ep));
-          tu_edpt_stream_open(&p_midi->ep_stream.rx, p_ep);
+          desc_cb.desc_epin      = p_ep;
+          ep_stream              = &p_midi->ep_stream.rx;
         }
+        TU_ASSERT(tuh_edpt_open(dev_addr, p_ep));
+        tu_edpt_stream_open(ep_stream, p_ep);
+        tu_edpt_stream_clear(ep_stream);
+
         break;
       }
 
@@ -379,8 +375,14 @@ bool tuh_midi_itf_get_info(uint8_t idx, tuh_itf_info_t* info) {
   desc->bDescriptorType    = TUSB_DESC_INTERFACE;
 
   desc->bInterfaceNumber   = p_midi->bInterfaceNumber;
-  desc->bAlternateSetting  = 0;
-  desc->bNumEndpoints      = (uint8_t)((p_midi->ep_in != 0 ? 1:0) + (p_midi->ep_out != 0 ? 1:0));
+  desc->bAlternateSetting = 0;
+  desc->bNumEndpoints     = 0;
+  if (tu_edpt_stream_is_opened(&p_midi->ep_stream.tx)) {
+    desc->bNumEndpoints++;
+  }
+  if (tu_edpt_stream_is_opened(&p_midi->ep_stream.rx)) {
+    desc->bNumEndpoints++;
+  }
   desc->bInterfaceClass    = TUSB_CLASS_AUDIO;
   desc->bInterfaceSubClass = AUDIO_SUBCLASS_MIDI_STREAMING;
   desc->bInterfaceProtocol = 0;
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index 27724b194..7da4d2239 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -202,8 +202,9 @@ void vendord_reset(uint8_t rhport) {
     vendord_interface_t* p_itf = &_vendord_itf[i];
     tu_memclr(p_itf, ITF_MEM_RESET_SIZE);
     tu_edpt_stream_clear(&p_itf->rx.stream);
-    tu_edpt_stream_clear(&p_itf->tx.stream);
     tu_edpt_stream_close(&p_itf->rx.stream);
+
+    tu_edpt_stream_clear(&p_itf->tx.stream);
     tu_edpt_stream_close(&p_itf->tx.stream);
   }
 }
@@ -233,16 +234,18 @@ uint16_t vendord_open(uint8_t rhport, const tusb_desc_interface_t* desc_itf, uin
       const tusb_desc_endpoint_t* desc_ep = (const tusb_desc_endpoint_t*) p_desc;
       TU_ASSERT(usbd_edpt_open(rhport, desc_ep));
 
-      // open endpoint stream, skip if already opened
+      // open endpoint stream, skip if already opened (multiple IN/OUT endpoints)
       if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN) {
-        if (p_vendor->tx.stream.ep_addr == 0) {
-          tu_edpt_stream_open(&p_vendor->tx.stream, desc_ep);
-          tud_vendor_n_write_flush(itf);
+        tu_edpt_stream_t *stream_tx = &p_vendor->tx.stream;
+        if (stream_tx->ep_addr == 0) {
+          tu_edpt_stream_open(stream_tx, desc_ep);
+          tu_edpt_stream_write_xfer(rhport, stream_tx); // flush pending data
         }
       } else {
-        if (p_vendor->rx.stream.ep_addr == 0) {
-          tu_edpt_stream_open(&p_vendor->rx.stream, desc_ep);
-          TU_ASSERT(tu_edpt_stream_read_xfer(rhport, &p_vendor->rx.stream) > 0, 0); // prepare for incoming data
+        tu_edpt_stream_t *stream_rx = &p_vendor->rx.stream;
+        if (stream_rx->ep_addr == 0) {
+          tu_edpt_stream_open(stream_rx, desc_ep);
+          TU_ASSERT(tu_edpt_stream_read_xfer(rhport, stream_rx) > 0, 0); // prepare for incoming data
         }
       }
     }
diff --git a/src/class/video/video_device.c b/src/class/video/video_device.c
index 85e85e75e..b2375def9 100644
--- a/src/class/video/video_device.c
+++ b/src/class/video/video_device.c
@@ -214,6 +214,12 @@ TU_ATTR_WEAK int tud_video_commit_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx,
   return VIDEO_ERROR_NONE;
 }
 
+TU_ATTR_WEAK void tud_video_prepare_payload_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, tud_video_payload_request_t* request) {
+  (void) ctl_idx;
+  (void) stm_idx;
+  (void) request;
+}
+
 //--------------------------------------------------------------------+
 //
 //--------------------------------------------------------------------+
@@ -874,7 +880,16 @@ static uint_fast16_t _prepare_in_payload(videod_streaming_interface_t *stm, uint
   }
   TU_ASSERT(pkt_len >= hdr_len);
   uint_fast16_t data_len = pkt_len - hdr_len;
-  memcpy(&ep_buf[hdr_len], stm->buffer + stm->offset, data_len);
+  if (stm->buffer) {
+    memcpy(&ep_buf[hdr_len], stm->buffer + stm->offset, data_len);
+  } else {
+    tud_video_payload_request_t rqst = {
+      .buf = &ep_buf[hdr_len],
+      .length = data_len,
+      .offset = stm->offset
+    };
+    tud_video_prepare_payload_cb(stm->index_vc, stm->index_vs, &rqst);
+  }
   stm->offset += data_len;
   remaining -= data_len;
   if (!remaining) {
@@ -1255,13 +1270,14 @@ bool tud_video_n_frame_xfer(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, void *bu
   TU_ASSERT(ctl_idx < CFG_TUD_VIDEO);
   TU_ASSERT(stm_idx < CFG_TUD_VIDEO_STREAMING);
 
-  if (NULL == buffer || 0 == bufsize) {
+  if (0 == bufsize) {
     return false;
   }
+
   videod_streaming_interface_t *stm = _get_instance_streaming(ctl_idx, stm_idx);
   videod_streaming_epbuf_t *stm_epbuf = &_videod_streaming_epbuf[ctl_idx];
 
-  if (NULL == stm || 0 == stm->desc.ep[0] || stm->buffer) {
+  if (NULL == stm || 0 == stm->desc.ep[0] || stm->bufsize) {
     return false;
   }
   if (stm->state == VS_STATE_PROBING) {
diff --git a/src/class/video/video_device.h b/src/class/video/video_device.h
index 2b41c3bfe..f14555e4f 100644
--- a/src/class/video/video_device.h
+++ b/src/class/video/video_device.h
@@ -35,6 +35,16 @@
 extern "C" {
 #endif
 
+
+//--------------------------------------------------------------------+
+// Payload request
+//--------------------------------------------------------------------+
+typedef struct TU_ATTR_PACKED {
+    void* buf;      /* Payload buffer to be filled */
+    size_t length;  /* Length of the requested data in bytes */
+    size_t offset;  /* Offset within the frame (in bytes) */
+} tud_video_payload_request_t;
+
 //--------------------------------------------------------------------+
 // Application API (Multiple Ports)
 // CFG_TUD_VIDEO > 1
@@ -83,6 +93,16 @@ int tud_video_power_mode_cb(uint_fast8_t ctl_idx, uint8_t power_mod);
 int tud_video_commit_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx,
                                      video_probe_and_commit_control_t const *parameters);
 
+/** Invoked if buffer is set to NULL (allows bufferless on the fly data generation)
+ *
+ * @param[in]   ctl_idx       Destination control interface index
+ * @param[in]   stm_idx       Destination streaming interface index
+ * @param[out]  payload_buf   Payload storage buffer (target buffer for requested data)
+ * @param[in]   payload_size  Size of payload_buf (requested data size)
+ * @param[in]   offset        Current byte offset relative to given bufsize from tud_video_n_frame_xfer (framesize)
+ * @return video_error_code_t */
+void tud_video_prepare_payload_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, tud_video_payload_request_t* request);
+
 //--------------------------------------------------------------------+
 // INTERNAL USBD-CLASS DRIVER API
 //--------------------------------------------------------------------+