Merge branch 'master' into fork/ennebi/mtp

26 files changed, 642 insertions, 378 deletions

diff --git a/src/class/audio/audio_device.c b/src/class/audio/audio_device.c
index bb906c7cf..701411401 100644
--- a/src/class/audio/audio_device.c
+++ b/src/class/audio/audio_device.c
@@ -192,17 +192,6 @@ tu_static CFG_TUD_MEM_SECTION struct {
   #endif
 } ctrl_buf;
 
-// Active alternate setting of interfaces
-tu_static uint8_t alt_setting_1[CFG_TUD_AUDIO_FUNC_1_N_AS_INT];
-
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_N_AS_INT > 0
-tu_static uint8_t alt_setting_2[CFG_TUD_AUDIO_FUNC_2_N_AS_INT];
-#endif
-
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_N_AS_INT > 0
-tu_static uint8_t alt_setting_3[CFG_TUD_AUDIO_FUNC_3_N_AS_INT];
-#endif
-
 // Aligned buffer for feedback EP
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 tu_static CFG_TUD_MEM_SECTION struct {
@@ -234,13 +223,14 @@ typedef struct
   uint8_t ep_in;            // TX audio data EP.
   uint16_t ep_in_sz;        // Current size of TX EP
   uint8_t ep_in_as_intf_num;// Corresponding Standard AS Interface Descriptor (4.9.1) belonging to output terminal to which this EP belongs - 0 is invalid (this fits to UAC2 specification since AS interfaces can not have interface number equal to zero)
-#endif
+  uint8_t ep_in_alt;        // Current alternate setting of TX EP
+  #endif
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
   uint8_t ep_out;            // Incoming (into uC) audio data EP.
   uint16_t ep_out_sz;        // Current size of RX EP
   uint8_t ep_out_as_intf_num;// Corresponding Standard AS Interface Descriptor (4.9.1) belonging to input terminal to which this EP belongs - 0 is invalid (this fits to UAC2 specification since AS interfaces can not have interface number equal to zero)
-
+  uint8_t ep_out_alt;        // Current alternate setting of RX EP
   #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
   uint8_t ep_fb;// Feedback EP.
   #endif
@@ -304,9 +294,6 @@ typedef struct
   uint8_t *ctrl_buf;
   uint8_t ctrl_buf_sz;
 
-  // Current active alternate settings
-  uint8_t *alt_setting;// We need to save the current alternate setting this way, because it is possible that there are AS interfaces which do not have an EP!
-
 // EP Transfer buffers and FIFOs
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
   tu_fifo_t ep_out_ff;
@@ -475,8 +462,6 @@ static bool audiod_tx_xfer_isr(uint8_t rhport, audiod_function_t* audio, uint16_
 static bool audiod_get_interface(uint8_t rhport, tusb_control_request_t const *p_request);
 static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p_request);
 
-static bool audiod_get_AS_interface_index_global(uint8_t itf, uint8_t *func_id, uint8_t *idxItf, uint8_t const **pp_desc_int);
-static bool audiod_get_AS_interface_index(uint8_t itf, audiod_function_t *audio, uint8_t *idxItf, uint8_t const **pp_desc_int);
 static bool audiod_verify_entity_exists(uint8_t itf, uint8_t entityID, uint8_t *func_id);
 static bool audiod_verify_itf_exists(uint8_t itf, uint8_t *func_id);
 static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *func_id);
@@ -529,11 +514,7 @@ tu_fifo_t *tud_audio_n_get_ep_out_ff(uint8_t func_id) {
 }
 
 static bool audiod_rx_xfer_isr(uint8_t rhport, audiod_function_t* audio, uint16_t n_bytes_received) {
-  uint8_t idxItf;
-  uint8_t const *dummy2;
-
   uint8_t idx_audio_fct = audiod_get_audio_fct_idx(audio);
-  TU_VERIFY(audiod_get_AS_interface_index(audio->ep_out_as_intf_num, audio, &idxItf, &dummy2));
 
   #if USE_LINEAR_BUFFER_RX
   // Data currently is in linear buffer, copy into EP OUT FIFO
@@ -553,7 +534,7 @@ static bool audiod_rx_xfer_isr(uint8_t rhport, audiod_function_t* audio, uint16_
   #endif
 
   // Call a weak callback here - a possibility for user to get informed an audio packet was received and data gets now loaded into EP FIFO
-  TU_VERIFY(tud_audio_rx_done_isr(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->alt_setting[idxItf]));
+  TU_VERIFY(tud_audio_rx_done_isr(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->ep_out_alt));
 
   return true;
 }
@@ -584,14 +565,10 @@ tu_fifo_t *tud_audio_n_get_ep_in_ff(uint8_t func_id) {
 }
 
 static bool audiod_tx_xfer_isr(uint8_t rhport, audiod_function_t * audio, uint16_t n_bytes_sent) {
-  uint8_t idxItf;
-  uint8_t const *dummy2;
-
   uint8_t idx_audio_fct = audiod_get_audio_fct_idx(audio);
-  TU_VERIFY(audiod_get_AS_interface_index(audio->ep_in_as_intf_num, audio, &idxItf, &dummy2));
 
   // Only send something if current alternate interface is not 0 as in this case nothing is to be sent due to UAC2 specifications
-  if (audio->alt_setting[idxItf] == 0) { return false; }
+  if (audio->ep_in_alt == 0) { return false; }
 
   // Send everything in ISO EP FIFO
   uint16_t n_bytes_tx;
@@ -611,7 +588,7 @@ static bool audiod_tx_xfer_isr(uint8_t rhport, audiod_function_t * audio, uint16
   #endif
 
   // Call a weak callback here - a possibility for user to get informed former TX was completed and data gets now loaded into EP in buffer
-  TU_VERIFY(tud_audio_tx_done_isr(rhport, n_bytes_sent, idx_audio_fct, audio->ep_in, audio->alt_setting[idxItf]));
+  TU_VERIFY(tud_audio_tx_done_isr(rhport, n_bytes_sent, idx_audio_fct, audio->ep_in, audio->ep_in_alt));
 
   return true;
 }
@@ -704,25 +681,6 @@ void audiod_init(void) {
 #endif
     }
 
-    // Initialize active alternate interface buffers
-    switch (i) {
-#if CFG_TUD_AUDIO_FUNC_1_N_AS_INT > 0
-      case 0:
-        audio->alt_setting = alt_setting_1;
-        break;
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_N_AS_INT > 0
-      case 1:
-        audio->alt_setting = alt_setting_2;
-        break;
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_N_AS_INT > 0
-      case 2:
-        audio->alt_setting = alt_setting_3;
-        break;
-#endif
-    }
-
       // Initialize IN EP FIFO if required
 #if CFG_TUD_AUDIO_ENABLE_EP_IN
 
@@ -1029,13 +987,25 @@ static bool audiod_get_interface(uint8_t rhport, tusb_control_request_t const *p
   uint8_t const itf = tu_u16_low(p_request->wIndex);
 
   // Find index of audio streaming interface
-  uint8_t func_id, idxItf;
-  uint8_t const *dummy;
+  uint8_t func_id;
+  TU_VERIFY(audiod_verify_itf_exists(itf, &func_id));
+
+  // Default to 0 if interface not yet activated
+  uint8_t alt = 0;
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+  if (_audiod_fct[func_id].ep_in_as_intf_num == itf) {
+    alt = _audiod_fct[func_id].ep_in_alt;
+  }
+#endif
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (_audiod_fct[func_id].ep_out_as_intf_num == itf) {
+    alt = _audiod_fct[func_id].ep_out_alt;
+  }
+#endif
 
-  TU_VERIFY(audiod_get_AS_interface_index_global(itf, &func_id, &idxItf, &dummy));
-  TU_VERIFY(tud_control_xfer(rhport, p_request, &_audiod_fct[func_id].alt_setting[idxItf], 1));
+  TU_VERIFY(tud_control_xfer(rhport, p_request, &alt, 1));
 
-  TU_LOG2("  Get itf: %u - current alt: %u\r\n", itf, _audiod_fct[func_id].alt_setting[idxItf]);
+  TU_LOG2("  Get itf: %u - current alt: %u\r\n", itf, alt);
 
   return true;
 }
@@ -1060,9 +1030,8 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
   TU_LOG2("  Set itf: %u - alt: %u\r\n", itf, alt);
 
   // Find index of audio streaming interface and index of interface
-  uint8_t func_id, idxItf;
-  uint8_t const *p_desc;
-  TU_VERIFY(audiod_get_AS_interface_index_global(itf, &func_id, &idxItf, &p_desc));
+  uint8_t func_id;
+  TU_VERIFY(audiod_verify_itf_exists(itf, &func_id));
 
   audiod_function_t *audio = &_audiod_fct[func_id];
 
@@ -1070,6 +1039,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
 #if CFG_TUD_AUDIO_ENABLE_EP_IN
   if (audio->ep_in_as_intf_num == itf) {
     audio->ep_in_as_intf_num = 0;
+    audio->ep_in_alt = 0;
   #ifndef TUP_DCD_EDPT_ISO_ALLOC
     usbd_edpt_close(rhport, audio->ep_in);
   #endif
@@ -1093,6 +1063,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
   if (audio->ep_out_as_intf_num == itf) {
     audio->ep_out_as_intf_num = 0;
+    audio->ep_out_alt = 0;
   #ifndef TUP_DCD_EDPT_ISO_ALLOC
     usbd_edpt_close(rhport, audio->ep_out);
   #endif
@@ -1116,10 +1087,10 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
   }
 #endif// CFG_TUD_AUDIO_ENABLE_EP_OUT
 
-  // Save current alternative interface setting
-  audio->alt_setting[idxItf] = alt;
-
   // Open new EP if necessary - EPs are only to be closed or opened for AS interfaces - Look for AS interface with correct alternate interface
+  uint8_t const *p_desc = tu_desc_next(audio->p_desc);
+  // Skip entire AC descriptor block
+  p_desc += ((audio_desc_cs_ac_interface_t const *) p_desc)->wTotalLength;
   // Get pointer at end
   uint8_t const *p_desc_end = audio->p_desc + audio->desc_length - TUD_AUDIO_DESC_IAD_LEN;
 
@@ -1154,6 +1125,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
             // Save address
             audio->ep_in = ep_addr;
             audio->ep_in_as_intf_num = itf;
+            audio->ep_in_alt = alt;
             audio->ep_in_sz = tu_edpt_packet_size(desc_ep);
 
             // If flow control is enabled, parse for the corresponding parameters - doing this here means only AS interfaces with EPs get scanned for parameters
@@ -1176,6 +1148,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *p
             // Save address
             audio->ep_out = ep_addr;
             audio->ep_out_as_intf_num = itf;
+            audio->ep_out_alt = alt;
             audio->ep_out_sz = tu_edpt_packet_size(desc_ep);
 
             // Prepare for incoming data
@@ -1474,8 +1447,7 @@ bool audiod_xfer_isr(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
 #if CFG_TUD_AUDIO_ENABLE_EP_IN
 
     // Data transmission of audio packet finished
-    if (audio->ep_in == ep_addr && audio->alt_setting != 0)
-    {
+    if (audio->ep_in == ep_addr) {
       // USB 2.0, section 5.6.4, third paragraph, states "An isochronous endpoint must specify its required bus access period. However, an isochronous endpoint must be prepared to handle poll rates faster than the one specified."
       // That paragraph goes on to say "An isochronous IN endpoint must return a zero-length packet whenever data is requested at a faster interval than the specified interval and data is not available."
       // This can only be solved reliably if we load a ZLP after every IN transmission since we can not say if the host requests samples earlier than we declared! Once all samples are collected we overwrite the loaded ZLP.
@@ -1492,8 +1464,7 @@ bool audiod_xfer_isr(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
     // New audio packet received
-    if (audio->ep_out == ep_addr)
-    {
+    if (audio->ep_out == ep_addr) {
       audiod_rx_xfer_isr(rhport, audio, (uint16_t) xferred_bytes);
       return true;
     }
@@ -1694,53 +1665,6 @@ bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_req
   return tud_control_xfer(rhport, p_request, (void *) _audiod_fct[func_id].ctrl_buf, len);
 }
 
-// This helper function finds for a given audio function and AS interface number the index of the attached driver structure, the index of the interface in the audio function
-// (e.g. the std. AS interface with interface number 15 is the first AS interface for the given audio function and thus gets index zero), and
-// finally a pointer to the std. AS interface, where the pointer always points to the first alternate setting i.e. alternate interface zero.
-static bool audiod_get_AS_interface_index(uint8_t itf, audiod_function_t *audio, uint8_t *idxItf, uint8_t const **pp_desc_int) {
-  if (audio->p_desc) {
-    // Get pointer at end
-    uint8_t const *p_desc_end = audio->p_desc + audio->desc_length - TUD_AUDIO_DESC_IAD_LEN;
-
-    // Advance past AC descriptors
-    uint8_t const *p_desc = tu_desc_next(audio->p_desc);
-    p_desc += ((audio_desc_cs_ac_interface_t const *) p_desc)->wTotalLength;
-
-    uint8_t tmp = 0;
-    // Condition modified from p_desc < p_desc_end to prevent gcc>=12 strict-overflow warning
-    while (p_desc_end - p_desc > 0) {
-      // We assume the number of alternate settings is increasing thus we return the index of alternate setting zero!
-      if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const *) p_desc)->bAlternateSetting == 0) {
-        if (((tusb_desc_interface_t const *) p_desc)->bInterfaceNumber == itf) {
-          *idxItf = tmp;
-          *pp_desc_int = p_desc;
-          return true;
-        }
-        // Increase index, bytes read, and pointer
-        tmp++;
-      }
-      p_desc = tu_desc_next(p_desc);
-    }
-  }
-  return false;
-}
-
-// This helper function finds for a given AS interface number the index of the attached driver structure, the index of the interface in the audio function
-// (e.g. the std. AS interface with interface number 15 is the first AS interface for the given audio function and thus gets index zero), and
-// finally a pointer to the std. AS interface, where the pointer always points to the first alternate setting i.e. alternate interface zero.
-static bool audiod_get_AS_interface_index_global(uint8_t itf, uint8_t *func_id, uint8_t *idxItf, uint8_t const **pp_desc_int) {
-  // Loop over audio driver interfaces
-  uint8_t i;
-  for (i = 0; i < CFG_TUD_AUDIO; i++) {
-    if (audiod_get_AS_interface_index(itf, &_audiod_fct[i], idxItf, pp_desc_int)) {
-      *func_id = i;
-      return true;
-    }
-  }
-
-  return false;
-}
-
 // Verify an entity with the given ID exists and returns also the corresponding driver index
 static bool audiod_verify_entity_exists(uint8_t itf, uint8_t entityID, uint8_t *func_id) {
   uint8_t i;
@@ -1754,8 +1678,8 @@ static bool audiod_verify_entity_exists(uint8_t itf, uint8_t entityID, uint8_t *
 
       // Condition modified from p_desc < p_desc_end to prevent gcc>=12 strict-overflow warning
       while (p_desc_end - p_desc > 0) {
-        if (p_desc[3] == entityID)// Entity IDs are always at offset 3
-        {
+        // Entity IDs are always at offset 3
+        if (p_desc[3] == entityID) {
           *func_id = i;
           return true;
         }
@@ -1775,7 +1699,7 @@ static bool audiod_verify_itf_exists(uint8_t itf, uint8_t *func_id) {
       uint8_t const *p_desc_end = _audiod_fct[i].p_desc + _audiod_fct[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
       // Condition modified from p_desc < p_desc_end to prevent gcc>=12 strict-overflow warning
       while (p_desc_end - p_desc > 0) {
-        if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const *) _audiod_fct[i].p_desc)->bInterfaceNumber == itf) {
+        if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const *)p_desc)->bInterfaceNumber == itf) {
           *func_id = i;
           return true;
         }
diff --git a/src/class/audio/audio_device.h b/src/class/audio/audio_device.h
index 6bcedc88c..fd47c649d 100644
--- a/src/class/audio/audio_device.h
+++ b/src/class/audio/audio_device.h
@@ -51,21 +51,6 @@
 #endif
 #endif
 
-// Number of Standard AS Interface Descriptors (4.9.1) defined per audio function - this is required to be able to remember the current alternate settings of these interfaces
-#ifndef CFG_TUD_AUDIO_FUNC_1_N_AS_INT
-#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
-#endif
-#if CFG_TUD_AUDIO > 1
-#ifndef CFG_TUD_AUDIO_FUNC_2_N_AS_INT
-#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
-#endif
-#endif
-#if CFG_TUD_AUDIO > 2
-#ifndef CFG_TUD_AUDIO_FUNC_3_N_AS_INT
-#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
-#endif
-#endif
-
 // Size of control buffer used to receive and send control messages via EP0 - has to be big enough to hold your biggest request structure e.g. range requests with multiple intervals defined or cluster descriptors
 #ifndef CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ
 #error You must define an audio class control request buffer size!
diff --git a/src/class/bth/bth_device.c b/src/class/bth/bth_device.c
index 45cbf2d98..3f1529cb6 100755
--- a/src/class/bth/bth_device.c
+++ b/src/class/bth/bth_device.c
@@ -43,7 +43,7 @@ typedef struct {
   uint8_t ep_acl_in;
   uint16_t ep_acl_in_pkt_sz;
   uint8_t ep_acl_out;
-  uint8_t ep_voice[2];  // Not used yet
+  uint8_t ep_voice[2];// Not used yet
   uint8_t ep_voice_size[2][CFG_TUD_BTH_ISO_ALT_COUNT];
 
   // Previous amount of bytes sent when issuing ZLP
@@ -61,8 +61,7 @@ typedef struct {
 static btd_interface_t _btd_itf;
 CFG_TUD_MEM_SECTION static btd_epbuf_t _btd_epbuf;
 
-static bool bt_tx_data(uint8_t ep, void *data, uint16_t len)
-{
+static bool bt_tx_data(uint8_t ep, void *data, uint16_t len) {
   uint8_t const rhport = 0;
 
   // skip if previous transfer not complete
@@ -74,6 +73,27 @@ static bool bt_tx_data(uint8_t ep, void *data, uint16_t len)
 }
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_bt_hci_cmd_cb(void *hci_cmd, size_t cmd_len) {
+  (void) hci_cmd;
+  (void) cmd_len;
+}
+
+TU_ATTR_WEAK void tud_bt_acl_data_received_cb(void *acl_data, uint16_t data_len) {
+  (void) acl_data;
+  (void) data_len;
+}
+
+TU_ATTR_WEAK void tud_bt_event_sent_cb(uint16_t sent_bytes) {
+  (void) sent_bytes;
+}
+
+TU_ATTR_WEAK void tud_bt_acl_data_sent_cb(uint16_t sent_bytes) {
+  (void) sent_bytes;
+}
+
+//--------------------------------------------------------------------+
 // READ API
 //--------------------------------------------------------------------+
 
@@ -82,13 +102,11 @@ static bool bt_tx_data(uint8_t ep, void *data, uint16_t len)
 // WRITE API
 //--------------------------------------------------------------------+
 
-bool tud_bt_event_send(void *event, uint16_t event_len)
-{
+bool tud_bt_event_send(void *event, uint16_t event_len) {
   return bt_tx_data(_btd_itf.ep_ev, event, event_len);
 }
 
-bool tud_bt_acl_data_send(void *event, uint16_t event_len)
-{
+bool tud_bt_acl_data_send(void *event, uint16_t event_len) {
   return bt_tx_data(_btd_itf.ep_acl_in, event, event_len);
 }
 
@@ -103,13 +121,11 @@ bool btd_deinit(void) {
   return true;
 }
 
-void btd_reset(uint8_t rhport)
-{
-  (void)rhport;
+void btd_reset(uint8_t rhport) {
+  (void) rhport;
 }
 
-uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_t max_len)
-{
+uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_t max_len) {
   tusb_desc_endpoint_t const *desc_ep;
   uint16_t drv_len = 0;
   // Size of single alternative of ISO interface
@@ -118,8 +134,9 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
   const uint16_t hci_itf_size = sizeof(tusb_desc_interface_t) + 3 * sizeof(tusb_desc_endpoint_t);
   // Ensure this is BT Primary Controller
   TU_VERIFY(TUSB_CLASS_WIRELESS_CONTROLLER == itf_desc->bInterfaceClass &&
-            TUD_BT_APP_SUBCLASS == itf_desc->bInterfaceSubClass &&
-            TUD_BT_PROTOCOL_PRIMARY_CONTROLLER == itf_desc->bInterfaceProtocol, 0);
+                TUD_BT_APP_SUBCLASS == itf_desc->bInterfaceSubClass &&
+                TUD_BT_PROTOCOL_PRIMARY_CONTROLLER == itf_desc->bInterfaceProtocol,
+            0);
 
   TU_ASSERT(itf_desc->bNumEndpoints == 3 && max_len >= hci_itf_size);
 
@@ -131,10 +148,10 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
   TU_ASSERT(usbd_edpt_open(rhport, desc_ep), 0);
   _btd_itf.ep_ev = desc_ep->bEndpointAddress;
 
-  desc_ep = (tusb_desc_endpoint_t const *)tu_desc_next(desc_ep);
+  desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(desc_ep);
 
   // Open endpoint pair
-  TU_ASSERT(usbd_open_edpt_pair(rhport, (uint8_t const *)desc_ep, 2,
+  TU_ASSERT(usbd_open_edpt_pair(rhport, (uint8_t const *) desc_ep, 2,
                                 TUSB_XFER_BULK, &_btd_itf.ep_acl_out,
                                 &_btd_itf.ep_acl_in),
             0);
@@ -146,10 +163,10 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
       _btd_itf.ep_acl_in_pkt_sz = tu_edpt_packet_size(desc_ep_acl_in);
       break;
     }
-    desc_ep_acl_in = (tusb_desc_endpoint_t const *)tu_desc_next(desc_ep_acl_in);
+    desc_ep_acl_in = (tusb_desc_endpoint_t const *) tu_desc_next(desc_ep_acl_in);
   }
 
-  itf_desc = (tusb_desc_interface_t const *)tu_desc_next(tu_desc_next(desc_ep));
+  itf_desc = (tusb_desc_interface_t const *) tu_desc_next(tu_desc_next(desc_ep));
 
   // Prepare for incoming data from host
   TU_ASSERT(usbd_edpt_xfer(rhport, _btd_itf.ep_acl_out, _btd_epbuf.epout_buf, CFG_TUD_BTH_DATA_EPSIZE), 0);
@@ -158,13 +175,14 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
 
   // Ensure this is still BT Primary Controller
   TU_ASSERT(TUSB_CLASS_WIRELESS_CONTROLLER == itf_desc->bInterfaceClass &&
-            TUD_BT_APP_SUBCLASS == itf_desc->bInterfaceSubClass &&
-            TUD_BT_PROTOCOL_PRIMARY_CONTROLLER == itf_desc->bInterfaceProtocol, 0);
+                TUD_BT_APP_SUBCLASS == itf_desc->bInterfaceSubClass &&
+                TUD_BT_PROTOCOL_PRIMARY_CONTROLLER == itf_desc->bInterfaceProtocol,
+            0);
   TU_ASSERT(itf_desc->bNumEndpoints == 2 && max_len >= iso_alt_itf_size + drv_len);
 
   uint8_t dir;
 
-  desc_ep = (tusb_desc_endpoint_t const *)tu_desc_next(itf_desc);
+  desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(itf_desc);
   TU_ASSERT(itf_desc->bAlternateSetting < CFG_TUD_BTH_ISO_ALT_COUNT, 0);
   TU_ASSERT(desc_ep->bDescriptorType == TUSB_DESC_ENDPOINT, 0);
   dir = tu_edpt_dir(desc_ep->bEndpointAddress);
@@ -172,7 +190,7 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
   // Store endpoint size for alternative
   _btd_itf.ep_voice_size[dir][itf_desc->bAlternateSetting] = (uint8_t) tu_edpt_packet_size(desc_ep);
 
-  desc_ep = (tusb_desc_endpoint_t const *)tu_desc_next(desc_ep);
+  desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(desc_ep);
   TU_ASSERT(desc_ep->bDescriptorType == TUSB_DESC_ENDPOINT, 0);
   dir = tu_edpt_dir(desc_ep->bEndpointAddress);
   _btd_itf.ep_voice[dir] = desc_ep->bEndpointAddress;
@@ -182,29 +200,30 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
 
   for (int i = 1; i < CFG_TUD_BTH_ISO_ALT_COUNT && drv_len + iso_alt_itf_size <= max_len; ++i) {
     // Make sure rest of alternatives matches
-    itf_desc = (tusb_desc_interface_t const *)tu_desc_next(desc_ep);
+    itf_desc = (tusb_desc_interface_t const *) tu_desc_next(desc_ep);
     if (itf_desc->bDescriptorType != TUSB_DESC_INTERFACE ||
         TUSB_CLASS_WIRELESS_CONTROLLER != itf_desc->bInterfaceClass ||
         TUD_BT_APP_SUBCLASS != itf_desc->bInterfaceSubClass ||
-        TUD_BT_PROTOCOL_PRIMARY_CONTROLLER != itf_desc->bInterfaceProtocol)
-    {
+        TUD_BT_PROTOCOL_PRIMARY_CONTROLLER != itf_desc->bInterfaceProtocol) {
       // Not an Iso interface instance
       break;
     }
     TU_ASSERT(itf_desc->bAlternateSetting < CFG_TUD_BTH_ISO_ALT_COUNT, 0);
 
-    desc_ep = (tusb_desc_endpoint_t const *)tu_desc_next(itf_desc);
+    desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(itf_desc);
     dir = tu_edpt_dir(desc_ep->bEndpointAddress);
     // Verify that alternative endpoint are same as first ones
     TU_ASSERT(desc_ep->bDescriptorType == TUSB_DESC_ENDPOINT &&
-              _btd_itf.ep_voice[dir] == desc_ep->bEndpointAddress, 0);
+                  _btd_itf.ep_voice[dir] == desc_ep->bEndpointAddress,
+              0);
     _btd_itf.ep_voice_size[dir][itf_desc->bAlternateSetting] = (uint8_t) tu_edpt_packet_size(desc_ep);
 
-    desc_ep = (tusb_desc_endpoint_t const *)tu_desc_next(desc_ep);
+    desc_ep = (tusb_desc_endpoint_t const *) tu_desc_next(desc_ep);
     dir = tu_edpt_dir(desc_ep->bEndpointAddress);
     // Verify that alternative endpoint are same as first ones
     TU_ASSERT(desc_ep->bDescriptorType == TUSB_DESC_ENDPOINT &&
-              _btd_itf.ep_voice[dir] == desc_ep->bEndpointAddress, 0);
+                  _btd_itf.ep_voice[dir] == desc_ep->bEndpointAddress,
+              0);
     _btd_itf.ep_voice_size[dir][itf_desc->bAlternateSetting] = (uint8_t) tu_edpt_packet_size(desc_ep);
     drv_len += iso_alt_itf_size;
   }
@@ -215,44 +234,32 @@ uint16_t btd_open(uint8_t rhport, tusb_desc_interface_t const *itf_desc, uint16_
 // Invoked when a control transfer occurred on an interface of this class
 // Driver response accordingly to the request and the transfer stage (setup/data/ack)
 // return false to stall control endpoint (e.g unsupported request)
-bool btd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const *request)
-{
-  (void)rhport;
+bool btd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const *request) {
+  (void) rhport;
 
-  if ( stage == CONTROL_STAGE_SETUP )
-  {
+  if (stage == CONTROL_STAGE_SETUP) {
     if (request->bmRequestType_bit.type == TUSB_REQ_TYPE_CLASS &&
-        request->bmRequestType_bit.recipient == TUSB_REQ_RCPT_DEVICE)
-    {
+        request->bmRequestType_bit.recipient == TUSB_REQ_RCPT_DEVICE) {
       // HCI command packet addressing for single function Primary Controllers
       // also compatible with historical mode if enabled
       TU_VERIFY((request->bRequest == 0 && request->wValue == 0 && request->wIndex == 0) ||
                 (CFG_TUD_BTH_HISTORICAL_COMPATIBLE && request->bRequest == 0xe0));
-    }
-    else if (request->bmRequestType_bit.recipient == TUSB_REQ_RCPT_INTERFACE)
-    {
-      if (request->bRequest == TUSB_REQ_SET_INTERFACE && _btd_itf.itf_num + 1 == request->wIndex)
-      {
+    } else if (request->bmRequestType_bit.recipient == TUSB_REQ_RCPT_INTERFACE) {
+      if (request->bRequest == TUSB_REQ_SET_INTERFACE && _btd_itf.itf_num + 1 == request->wIndex) {
         // TODO: Set interface it would involve changing size of endpoint size
-      }
-      else
-      {
+      } else {
         // HCI command packet for Primary Controller function in a composite device
         TU_VERIFY(request->bRequest == 0 && request->wValue == 0 && request->wIndex == _btd_itf.itf_num);
       }
-    }
-    else return false;
+    } else
+      return false;
 
     return tud_control_xfer(rhport, request, &_btd_epbuf.hci_cmd, sizeof(bt_hci_cmd_t));
-  }
-  else if ( stage == CONTROL_STAGE_DATA )
-  {
+  } else if (stage == CONTROL_STAGE_DATA) {
     // Handle class request only
     TU_VERIFY(request->bmRequestType_bit.type == TUSB_REQ_TYPE_CLASS);
 
-    if (tud_bt_hci_cmd_cb) {
-      tud_bt_hci_cmd_cb(&_btd_epbuf.hci_cmd, tu_min16(request->wLength, sizeof(bt_hci_cmd_t)));
-      }
+    tud_bt_hci_cmd_cb(&_btd_epbuf.hci_cmd, tu_min16(request->wLength, sizeof(bt_hci_cmd_t)));
   }
 
   return true;
@@ -261,19 +268,14 @@ bool btd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t c
 bool btd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result,
                  uint32_t xferred_bytes) {
   // received new data from host
-  if (ep_addr == _btd_itf.ep_acl_out)
-  {
-    if (tud_bt_acl_data_received_cb) tud_bt_acl_data_received_cb(_btd_epbuf.epout_buf, xferred_bytes);
+  if (ep_addr == _btd_itf.ep_acl_out) {
+    tud_bt_acl_data_received_cb(_btd_epbuf.epout_buf, xferred_bytes);
 
     // prepare for next data
     TU_ASSERT(usbd_edpt_xfer(rhport, _btd_itf.ep_acl_out, _btd_epbuf.epout_buf, CFG_TUD_BTH_DATA_EPSIZE));
-  }
-  else if (ep_addr == _btd_itf.ep_ev)
-  {
-    if (tud_bt_event_sent_cb) tud_bt_event_sent_cb((uint16_t)xferred_bytes);
-  }
-  else if (ep_addr == _btd_itf.ep_acl_in)
-  {
+  } else if (ep_addr == _btd_itf.ep_ev) {
+    tud_bt_event_sent_cb((uint16_t) xferred_bytes);
+  } else if (ep_addr == _btd_itf.ep_acl_in) {
     if ((result == XFER_RESULT_SUCCESS) && (xferred_bytes > 0) &&
         ((xferred_bytes & (_btd_itf.ep_acl_in_pkt_sz - 1)) == 0)) {
       // Save number of transferred bytes
@@ -281,12 +283,12 @@ bool btd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result,
 
       // Send zero-length packet
       tud_bt_acl_data_send(NULL, 0);
-    } else if (tud_bt_acl_data_sent_cb) {
+    } else {
       if (xferred_bytes == 0) {
         xferred_bytes = _btd_itf.prev_xferred_bytes;
         _btd_itf.prev_xferred_bytes = 0;
       }
-      tud_bt_acl_data_sent_cb((uint16_t)xferred_bytes);
+      tud_bt_acl_data_sent_cb((uint16_t) xferred_bytes);
     }
   }
 
diff --git a/src/class/bth/bth_device.h b/src/class/bth/bth_device.h
index 4f6350839..68f073bff 100755
--- a/src/class/bth/bth_device.h
+++ b/src/class/bth/bth_device.h
@@ -67,23 +67,23 @@ typedef struct TU_ATTR_PACKED
 // Part E, 5.4.1.
 // Length of the command is from 3 bytes (2 bytes for OpCode,
 // 1 byte for parameter total length) to 258.
-TU_ATTR_WEAK void tud_bt_hci_cmd_cb(void *hci_cmd, size_t cmd_len);
+void tud_bt_hci_cmd_cb(void *hci_cmd, size_t cmd_len);
 
 // Invoked when ACL data was received over USB from Bluetooth host.
 // Detailed format is described in Bluetooth core specification Vol 2,
 // Part E, 5.4.2.
 // Length is from 4 bytes, (12 bits for Handle, 4 bits for flags
 // and 16 bits for data total length) to endpoint size.
-TU_ATTR_WEAK void tud_bt_acl_data_received_cb(void *acl_data, uint16_t data_len);
+void tud_bt_acl_data_received_cb(void *acl_data, uint16_t data_len);
 
 // Called when event sent with tud_bt_event_send() was delivered to BT stack.
 // Controller can release/reuse buffer with Event packet at this point.
-TU_ATTR_WEAK void tud_bt_event_sent_cb(uint16_t sent_bytes);
+void tud_bt_event_sent_cb(uint16_t sent_bytes);
 
 // Called when ACL data that was sent with tud_bt_acl_data_send()
 // was delivered to BT stack.
 // Controller can release/reuse buffer with ACL packet at this point.
-TU_ATTR_WEAK void tud_bt_acl_data_sent_cb(uint16_t sent_bytes);
+void tud_bt_acl_data_sent_cb(uint16_t sent_bytes);
 
 // Bluetooth controller calls this function when it wants to send even packet
 // as described in Bluetooth core specification Vol 2, Part E, 5.4.4.
diff --git a/src/class/cdc/cdc_device.c b/src/class/cdc/cdc_device.c
index 4e4e01eaf..f1c4a3bbf 100644
--- a/src/class/cdc/cdc_device.c
+++ b/src/class/cdc/cdc_device.c
@@ -120,6 +120,42 @@ static bool _prep_out_transaction(uint8_t itf) {
 }
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_cdc_rx_cb(uint8_t itf) {
+  (void) itf;
+}
+
+TU_ATTR_WEAK void tud_cdc_rx_wanted_cb(uint8_t itf, char wanted_char) {
+  (void) itf;
+  (void) wanted_char;
+}
+
+TU_ATTR_WEAK void tud_cdc_tx_complete_cb(uint8_t itf) {
+  (void) itf;
+}
+
+TU_ATTR_WEAK void tud_cdc_notify_complete_cb(uint8_t 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;
+}
+
+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_send_break_cb(uint8_t itf, uint16_t duration_ms) {
+  (void) itf;
+  (void) duration_ms;
+}
+
+//--------------------------------------------------------------------+
 // APPLICATION API
 //--------------------------------------------------------------------+
 bool tud_cdc_configure(const tud_cdc_configure_t* driver_cfg) {
@@ -419,9 +455,7 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
         TU_LOG_DRV("  Set Line Coding\r\n");
         tud_control_xfer(rhport, request, &p_cdc->line_coding, sizeof(cdc_line_coding_t));
       } else if (stage == CONTROL_STAGE_ACK) {
-        if (tud_cdc_line_coding_cb) {
-          tud_cdc_line_coding_cb(itf, &p_cdc->line_coding);
-        }
+        tud_cdc_line_coding_cb(itf, &p_cdc->line_coding);
       }
       break;
 
@@ -456,9 +490,7 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
         TU_LOG_DRV("  Set Control Line State: DTR = %d, RTS = %d\r\n", dtr, rts);
 
         // Invoke callback
-        if (tud_cdc_line_state_cb) {
-          tud_cdc_line_state_cb(itf, dtr, rts);
-        }
+        tud_cdc_line_state_cb(itf, dtr, rts);
       }
       break;
 
@@ -467,9 +499,7 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_requ
         tud_control_status(rhport, request);
       } else if (stage == CONTROL_STAGE_ACK) {
         TU_LOG_DRV("  Send Break\r\n");
-        if (tud_cdc_send_break_cb) {
-          tud_cdc_send_break_cb(itf, request->wValue);
-        }
+        tud_cdc_send_break_cb(itf, request->wValue);
       }
       break;
 
@@ -501,7 +531,7 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
     tu_fifo_write_n(&p_cdc->rx_ff, p_epbuf->epout, (uint16_t) xferred_bytes);
 
     // Check for wanted char and invoke callback if needed
-    if (tud_cdc_rx_wanted_cb && (((signed char) p_cdc->wanted_char) != -1)) {
+    if (((signed char) p_cdc->wanted_char) != -1) {
       for (uint32_t i = 0; i < xferred_bytes; i++) {
         if ((p_cdc->wanted_char == p_epbuf->epout[i]) && !tu_fifo_empty(&p_cdc->rx_ff)) {
           tud_cdc_rx_wanted_cb(itf, p_cdc->wanted_char);
@@ -510,7 +540,7 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
     }
 
     // invoke receive callback (if there is still data)
-    if (tud_cdc_rx_cb && !tu_fifo_empty(&p_cdc->rx_ff)) {
+    if (!tu_fifo_empty(&p_cdc->rx_ff)) {
       tud_cdc_rx_cb(itf);
     }
 
@@ -523,9 +553,7 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
   //       Though maybe the baudrate is not really important !!!
   if (ep_addr == p_cdc->ep_in) {
     // invoke transmit callback to possibly refill tx fifo
-    if (tud_cdc_tx_complete_cb) {
-      tud_cdc_tx_complete_cb(itf);
-    }
+    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
@@ -540,9 +568,7 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
 
   // Sent notification to host
   if (ep_addr == p_cdc->ep_notify) {
-    if (tud_cdc_notify_complete_cb) {
-      tud_cdc_notify_complete_cb(itf);
-    }
+    tud_cdc_notify_complete_cb(itf);
   }
 
   return true;
diff --git a/src/class/cdc/cdc_device.h b/src/class/cdc/cdc_device.h
index a34e07e1d..9673b9807 100644
--- a/src/class/cdc/cdc_device.h
+++ b/src/class/cdc/cdc_device.h
@@ -220,28 +220,28 @@ TU_ATTR_ALWAYS_INLINE static inline bool tud_cdc_write_clear(void) {
 //--------------------------------------------------------------------+
 
 // Invoked when received new data
-TU_ATTR_WEAK void tud_cdc_rx_cb(uint8_t itf);
+void tud_cdc_rx_cb(uint8_t itf);
 
 // Invoked when received `wanted_char`
-TU_ATTR_WEAK void tud_cdc_rx_wanted_cb(uint8_t itf, char wanted_char);
+void tud_cdc_rx_wanted_cb(uint8_t itf, char wanted_char);
 
 // Invoked when a TX is complete and therefore space becomes available in TX buffer
-TU_ATTR_WEAK void tud_cdc_tx_complete_cb(uint8_t itf);
+void tud_cdc_tx_complete_cb(uint8_t itf);
 
 // Invoked when a notification is sent to host
-TU_ATTR_WEAK void tud_cdc_notify_complete_cb(uint8_t itf);
+void tud_cdc_notify_complete_cb(uint8_t itf);
 
 // Invoked when line state DTR & RTS are changed via SET_CONTROL_LINE_STATE
-TU_ATTR_WEAK void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts);
+void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts);
 
 // Invoked when line coding is change via SET_LINE_CODING
-TU_ATTR_WEAK void tud_cdc_line_coding_cb(uint8_t itf, cdc_line_coding_t const* p_line_coding);
+void tud_cdc_line_coding_cb(uint8_t itf, cdc_line_coding_t const* p_line_coding);
 
 // Invoked when received send break
 // \param[in]  itf  interface for which send break was received.
 // \param[in]  duration_ms  the length of time, in milliseconds, of the break signal. If a value of FFFFh, then the
 //                          device will send a break until another SendBreak request is received with value 0000h.
-TU_ATTR_WEAK void tud_cdc_send_break_cb(uint8_t itf, uint16_t duration_ms);
+void tud_cdc_send_break_cb(uint8_t itf, uint16_t duration_ms);
 
 //--------------------------------------------------------------------+
 // INTERNAL USBD-CLASS DRIVER API
diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index f9a37ed35..beef03eff 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -392,6 +392,25 @@ static cdch_interface_t * make_new_itf(uint8_t daddr, tusb_desc_interface_t cons
 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
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tuh_cdc_mount_cb(uint8_t idx) {
+  (void) idx;
+}
+
+TU_ATTR_WEAK void tuh_cdc_umount_cb(uint8_t idx) {
+  (void) idx;
+}
+
+TU_ATTR_WEAK void tuh_cdc_rx_cb(uint8_t idx) {
+  (void) idx;
+}
+
+TU_ATTR_WEAK void tuh_cdc_tx_complete_cb(uint8_t idx) {
+  (void) idx;
+}
+
+//--------------------------------------------------------------------+
 // APPLICATION API
 //--------------------------------------------------------------------+
 
@@ -657,9 +676,7 @@ void cdch_close(uint8_t daddr) {
       TU_LOG_CDC(p_cdc, "close");
 
       // Invoke application callback
-      if (tuh_cdc_umount_cb) {
-        tuh_cdc_umount_cb(idx);
-      }
+      tuh_cdc_umount_cb(idx);
 
       p_cdc->daddr = 0;
       p_cdc->bInterfaceNumber = 0;
@@ -680,9 +697,7 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
 
   if (ep_addr == p_cdc->stream.tx.ep_addr) {
     // invoke tx complete callback to possibly refill tx fifo
-    if (tuh_cdc_tx_complete_cb) {
-      tuh_cdc_tx_complete_cb(idx);
-    }
+    tuh_cdc_tx_complete_cb(idx);
 
     if (0 == tu_edpt_stream_write_xfer(daddr, &p_cdc->stream.tx)) {
       // If there is no data left, a ZLP should be sent if:
@@ -697,18 +712,14 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
       if (xferred_bytes > 2) {
         tu_edpt_stream_read_xfer_complete_with_buf(&p_cdc->stream.rx, p_cdc->stream.rx.ep_buf + 2, xferred_bytes - 2);
 
-        if (tuh_cdc_rx_cb) {
-          tuh_cdc_rx_cb(idx); // invoke receive callback
-        }
+        tuh_cdc_rx_cb(idx); // invoke receive callback
       }
     } else
     #endif
     {
       tu_edpt_stream_read_xfer_complete(&p_cdc->stream.rx, xferred_bytes);
 
-      if (tuh_cdc_rx_cb) {
-        tuh_cdc_rx_cb(idx); // invoke receive callback
-      }
+      tuh_cdc_rx_cb(idx); // invoke receive callback
     }
 
     // prepare for next transfer if needed
@@ -794,9 +805,7 @@ static void set_config_complete(cdch_interface_t *p_cdc, bool success) {
   if (success) {
     const uint8_t idx = get_idx_by_ptr(p_cdc);
     p_cdc->mounted = true;
-    if (tuh_cdc_mount_cb) {
-      tuh_cdc_mount_cb(idx);
-    }
+    tuh_cdc_mount_cb(idx);
     // Prepare for incoming data
     tu_edpt_stream_read_xfer(p_cdc->daddr, &p_cdc->stream.rx);
   } else {
diff --git a/src/class/cdc/cdc_host.h b/src/class/cdc/cdc_host.h
index 37bfca270..bf6711d7e 100644
--- a/src/class/cdc/cdc_host.h
+++ b/src/class/cdc/cdc_host.h
@@ -230,16 +230,16 @@ TU_ATTR_ALWAYS_INLINE static inline tusb_xfer_result_t tuh_cdc_disconnect_sync(u
 
 // Invoked when a device with CDC interface is mounted
 // idx is index of cdc interface in the internal pool.
-TU_ATTR_WEAK extern void tuh_cdc_mount_cb(uint8_t idx);
+extern void tuh_cdc_mount_cb(uint8_t idx);
 
 // Invoked when a device with CDC interface is unmounted
-TU_ATTR_WEAK extern void tuh_cdc_umount_cb(uint8_t idx);
+extern void tuh_cdc_umount_cb(uint8_t idx);
 
 // Invoked when received new data
-TU_ATTR_WEAK extern void tuh_cdc_rx_cb(uint8_t idx);
+extern void tuh_cdc_rx_cb(uint8_t idx);
 
 // Invoked when a TX is complete and therefore space becomes available in TX buffer
-TU_ATTR_WEAK extern void tuh_cdc_tx_complete_cb(uint8_t idx);
+extern void tuh_cdc_tx_complete_cb(uint8_t idx);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/cdc/cdc_rndis_host.c b/src/class/cdc/cdc_rndis_host.c
index 11a5355aa..e975ea440 100644
--- a/src/class/cdc/cdc_rndis_host.c
+++ b/src/class/cdc/cdc_rndis_host.c
@@ -103,7 +103,7 @@ static tusb_error_t rndis_body_subtask(void)
 
   }
 
-  osal_task_delay(100);
+  tusb_time_delay_ms_api(100);
 
   OSAL_SUBTASK_END
 }
diff --git a/src/class/dfu/dfu_device.c b/src/class/dfu/dfu_device.c
index d9e2d3f2f..0d2b63b57 100644
--- a/src/class/dfu/dfu_device.c
+++ b/src/class/dfu/dfu_device.c
@@ -77,6 +77,24 @@ static bool process_download_get_status(uint8_t rhport, uint8_t stage, const tus
 static bool process_manifest_get_status(uint8_t rhport, uint8_t stage, const tusb_control_request_t* request);
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_dfu_detach_cb(void) {
+}
+
+TU_ATTR_WEAK void tud_dfu_abort_cb(uint8_t alt) {
+  (void) alt;
+}
+
+TU_ATTR_WEAK uint16_t tud_dfu_upload_cb(uint8_t alt, uint16_t block_num, uint8_t* data, uint16_t length) {
+  (void) alt;
+  (void) block_num;
+  (void) data;
+  (void) length;
+  return 0;
+}
+
+//--------------------------------------------------------------------+
 // Debug
 //--------------------------------------------------------------------+
 #if CFG_TUSB_DEBUG >= 2
@@ -234,9 +252,7 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
         if (stage == CONTROL_STAGE_SETUP) {
           tud_control_status(rhport, request);
         } else if (stage == CONTROL_STAGE_ACK) {
-          if (tud_dfu_detach_cb) {
-            tud_dfu_detach_cb();
-          }
+          tud_dfu_detach_cb();
         }
         break;
 
@@ -258,16 +274,13 @@ bool dfu_moded_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control
           reset_state();
           tud_control_status(rhport, request);
         } else if (stage == CONTROL_STAGE_ACK) {
-          if (tud_dfu_abort_cb) {
-            tud_dfu_abort_cb(_dfu_ctx.alt);
-          }
+          tud_dfu_abort_cb(_dfu_ctx.alt);
         }
         break;
 
       case DFU_REQUEST_UPLOAD:
         if (stage == CONTROL_STAGE_SETUP) {
           TU_VERIFY(_dfu_ctx.attrs & DFU_ATTR_CAN_UPLOAD);
-          TU_VERIFY(tud_dfu_upload_cb);
           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,
diff --git a/src/class/dfu/dfu_device.h b/src/class/dfu/dfu_device.h
index 00c22ea8b..e59e61ce9 100644
--- a/src/class/dfu/dfu_device.h
+++ b/src/class/dfu/dfu_device.h
@@ -74,13 +74,13 @@ void tud_dfu_manifest_cb(uint8_t alt);
 // Invoked when received DFU_UPLOAD request
 // Application must populate data with up to length bytes and
 // Return the number of written bytes
-TU_ATTR_WEAK uint16_t tud_dfu_upload_cb(uint8_t alt, uint16_t block_num, uint8_t* data, uint16_t length);
+uint16_t tud_dfu_upload_cb(uint8_t alt, uint16_t block_num, uint8_t* data, uint16_t length);
 
 // Invoked when a DFU_DETACH request is received
-TU_ATTR_WEAK void tud_dfu_detach_cb(void);
+void tud_dfu_detach_cb(void);
 
 // Invoked when the Host has terminated a download or upload transfer
-TU_ATTR_WEAK void tud_dfu_abort_cb(uint8_t alt);
+void tud_dfu_abort_cb(uint8_t alt);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/hid/hid.h b/src/class/hid/hid.h
index bbc58af80..b69f623a0 100644
--- a/src/class/hid/hid.h
+++ b/src/class/hid/hid.h
@@ -807,7 +807,9 @@ enum {
   HID_USAGE_PAGE_MEDICAL_INSTRUMENT        = 0x40,
   HID_USAGE_PAGE_LIGHTING_AND_ILLUMINATION = 0x59,
   HID_USAGE_PAGE_MONITOR                   = 0x80, // 0x80 - 0x83
-  HID_USAGE_PAGE_POWER                     = 0x84, // 0x084 - 0x87
+  HID_USAGE_PAGE_POWER                     = 0x84,
+  HID_USAGE_PAGE_BATTERY                   = 0x85,
+  // 0x86 - 0x87 is reserved for Power Device
   HID_USAGE_PAGE_BARCODE_SCANNER           = 0x8c,
   HID_USAGE_PAGE_SCALE                     = 0x8d,
   HID_USAGE_PAGE_MSR                       = 0x8e,
@@ -1595,6 +1597,200 @@ enum {
   HID_USAGE_LIGHTING_AUTONOMOUS_MODE                     = 0x71,
 };
 
+/// HID Usage Table: Power Device Page (0x84)
+enum {
+  HID_USAGE_POWER_UNDEFINED              = 0x00,
+  HID_USAGE_POWER_I_NAME                 = 0x01,
+  HID_USAGE_POWER_PRESENT_STATUS         = 0x02,
+  HID_USAGE_POWER_CHANGED_STATUS         = 0x03,
+  HID_USAGE_POWER_UPS                    = 0x04,
+  HID_USAGE_POWER_POWER_SUPPLY           = 0x05,
+  // 06-0F Reserved
+  HID_USAGE_POWER_BATTERY_SYSTEM         = 0x10,
+  HID_USAGE_POWER_BATTERY_SYSTEM_ID      = 0x11,
+  HID_USAGE_POWER_BATTERY                = 0x12,
+  HID_USAGE_POWER_BATTERY_ID             = 0x13,
+  HID_USAGE_POWER_CHARGER                = 0x14,
+  HID_USAGE_POWER_CHARGER_ID             = 0x15,
+  HID_USAGE_POWER_POWER_CONVERTER        = 0x16,
+  HID_USAGE_POWER_POWER_CONVERTER_ID     = 0x17,
+  HID_USAGE_POWER_OUTLET_SYSTEM          = 0x18,
+  HID_USAGE_POWER_OUTLET_SYSTEM_ID       = 0x19,
+  HID_USAGE_POWER_INPUT                  = 0x1A,
+  HID_USAGE_POWER_INPUT_ID               = 0x1B,
+  HID_USAGE_POWER_OUTPUT                 = 0x1C,
+  HID_USAGE_POWER_OUTPUT_ID              = 0x1D,
+  HID_USAGE_POWER_FLOW                   = 0x1E,
+  HID_USAGE_POWER_FLOW_ID                = 0x1F,
+  HID_USAGE_POWER_OUTLET                 = 0x20,
+  HID_USAGE_POWER_OUTLET_ID              = 0x21,
+  HID_USAGE_POWER_GANG                   = 0x22,
+  HID_USAGE_POWER_GANG_ID                = 0x23,
+  HID_USAGE_POWER_POWER_SUMMARY          = 0x24,
+  HID_USAGE_POWER_POWER_SUMMARY_ID       = 0x25,
+  // 26-2F Reserved
+  HID_USAGE_POWER_VOLTAGE                = 0x30,
+  HID_USAGE_POWER_CURRENT                = 0x31,
+  HID_USAGE_POWER_FREQUENCY              = 0x32,
+  HID_USAGE_POWER_APPARENT_POWER         = 0x33,
+  HID_USAGE_POWER_ACTIVE_POWER           = 0x34,
+  HID_USAGE_POWER_PERCENT_LOAD           = 0x35,
+  HID_USAGE_POWER_TEMPERATURE            = 0x36,
+  HID_USAGE_POWER_HUMIDITY               = 0x37,
+  HID_USAGE_POWER_BAD_COUNT              = 0x38,
+  // 39-3F Reserved
+  HID_USAGE_POWER_CONFIG_VOLTAGE         = 0x40,
+  HID_USAGE_POWER_CONFIG_CURRENT         = 0x41,
+  HID_USAGE_POWER_CONFIG_FREQUENCY       = 0x42,
+  HID_USAGE_POWER_CONFIG_APPARENT_POWER  = 0x43,
+  HID_USAGE_POWER_CONFIG_ACTIVE_POWER    = 0x44,
+  HID_USAGE_POWER_CONFIG_PERCENT_LOAD    = 0x45,
+  HID_USAGE_POWER_CONFIG_TEMPERATURE     = 0x46,
+  HID_USAGE_POWER_CONFIG_HUMIDITY        = 0x47,
+  // 48-4F Reserved
+  HID_USAGE_POWER_SWITCH_ON_CONTROL      = 0x50,
+  HID_USAGE_POWER_SWITCH_OFF_CONTROL     = 0x51,
+  HID_USAGE_POWER_TOGGLE_CONTROL         = 0x52,
+  HID_USAGE_POWER_LOW_VOLTAGE_TRANSFER   = 0x53,
+  HID_USAGE_POWER_HIGH_VOLTAGE_TRANSFER  = 0x54,
+  HID_USAGE_POWER_DELAY_BEFORE_REBOOT    = 0x55,
+  HID_USAGE_POWER_DELAY_BEFORE_STARTUP   = 0x56,
+  HID_USAGE_POWER_DELAY_BEFORE_SHUTDOWN  = 0x57,
+  HID_USAGE_POWER_TEST                   = 0x58,
+  HID_USAGE_POWER_MODULE_RESET           = 0x59,
+  HID_USAGE_POWER_AUDIBLE_ALARM_CONTROL  = 0x5A,
+  // 5B-5F Reserved
+  HID_USAGE_POWER_PRESENT                = 0x60,
+  HID_USAGE_POWER_GOOD                   = 0x61,
+  HID_USAGE_POWER_INTERNAL_FAILURE       = 0x62,
+  HID_USAGE_POWER_VOLTAGE_OUT_OF_RANGE   = 0x63,
+  HID_USAGE_POWER_FREQUENCY_OUT_OF_RANGE = 0x64,
+  HID_USAGE_POWER_OVERLOAD               = 0x65,
+  HID_USAGE_POWER_OVER_CHARGED           = 0x66,
+  HID_USAGE_POWER_OVER_TEMPERATURE       = 0x67,
+  HID_USAGE_POWER_SHUTDOWN_REQUESTED     = 0x68,
+  HID_USAGE_POWER_SHUTDOWN_IMMINENT      = 0x69,
+  // 6A Reserved
+  HID_USAGE_POWER_SWITCH_ON_OFF          = 0x6B,
+  HID_USAGE_POWER_SWITCHABLE             = 0x6C,
+  HID_USAGE_POWER_USED                   = 0x6D,
+  HID_USAGE_POWER_BOOST                  = 0x6E,
+  HID_USAGE_POWER_BUCK                   = 0x6F,
+  HID_USAGE_POWER_INITIALIZED            = 0x70,
+  HID_USAGE_POWER_TESTED                 = 0x71,
+  HID_USAGE_POWER_AWAITING_POWER         = 0x72,
+  HID_USAGE_POWER_COMMUNICATION_LOST     = 0x73,
+  // 74-FC Reserved
+  HID_USAGE_POWER_I_MANUFACTURER         = 0xFD,
+  HID_USAGE_POWER_I_PRODUCT              = 0xFE,
+  HID_USAGE_POWER_I_SERIAL_NUMBER        = 0xFF
+};
+
+/// HID Usage Table: Battery System Page (0x85)
+enum {
+  HID_USAGE_BATTERY_UNDEFINED                      = 0x00,
+  HID_USAGE_BATTERY_SMB_BATTERY_MODE               = 0x01,
+  HID_USAGE_BATTERY_SMB_BATTERY_STATUS             = 0x02,
+  HID_USAGE_BATTERY_SMB_ALARM_WARNING              = 0x03,
+  HID_USAGE_BATTERY_SMB_CHARGER_MODE               = 0x04,
+  HID_USAGE_BATTERY_SMB_CHARGER_STATUS             = 0x05,
+  HID_USAGE_BATTERY_SMB_CHARGER_SPEC_INFO          = 0x06,
+  HID_USAGE_BATTERY_SMB_SELECTOR_STATE             = 0x07,
+  HID_USAGE_BATTERY_SMB_SELECTOR_PRESETS           = 0x08,
+  HID_USAGE_BATTERY_SMB_SELECTOR_INFO              = 0x09,
+  // 0A-0F Reserved
+  HID_USAGE_BATTERY_OPTIONAL_MFG_FUNCTION_1        = 0x10,
+  HID_USAGE_BATTERY_OPTIONAL_MFG_FUNCTION_2        = 0x11,
+  HID_USAGE_BATTERY_OPTIONAL_MFG_FUNCTION_3        = 0x12,
+  HID_USAGE_BATTERY_OPTIONAL_MFG_FUNCTION_4        = 0x13,
+  HID_USAGE_BATTERY_OPTIONAL_MFG_FUNCTION_5        = 0x14,
+  HID_USAGE_BATTERY_CONNECTION_TO_SMBUS            = 0x15,
+  HID_USAGE_BATTERY_OUTPUT_CONNECTION              = 0x16,
+  HID_USAGE_BATTERY_CHARGER_CONNECTION             = 0x17,
+  HID_USAGE_BATTERY_BATTERY_INSERTION              = 0x18,
+  HID_USAGE_BATTERY_USE_NEXT                       = 0x19,
+  HID_USAGE_BATTERY_OK_TO_USE                      = 0x1A,
+  HID_USAGE_BATTERY_BATTERY_SUPPORTED              = 0x1B,
+  HID_USAGE_BATTERY_SELECTOR_REVISION              = 0x1C,
+  HID_USAGE_BATTERY_CHARGING_INDICATOR             = 0x1D,
+  // 1E-27 Reserved
+  HID_USAGE_BATTERY_MANUFACTURER_ACCESS            = 0x28,
+  HID_USAGE_BATTERY_REMAINING_CAPACITY_LIMIT       = 0x29,
+  HID_USAGE_BATTERY_REMAINING_TIME_LIMIT           = 0x2A,
+  HID_USAGE_BATTERY_AT_RATE                        = 0x2B,
+  HID_USAGE_BATTERY_CAPACITY_MODE                  = 0x2C,
+  HID_USAGE_BATTERY_BROADCAST_TO_CHARGER           = 0x2D,
+  HID_USAGE_BATTERY_PRIMARY_BATTERY                = 0x2E,
+  HID_USAGE_BATTERY_CHARGE_CONTROLLER              = 0x2F,
+  // 30-3F Reserved
+  HID_USAGE_BATTERY_TERMINATE_CHARGE               = 0x40,
+  HID_USAGE_BATTERY_TERMINATE_DISCHARGE            = 0x41,
+  HID_USAGE_BATTERY_BELOW_REMAINING_CAPACITY_LIMIT = 0x42,
+  HID_USAGE_BATTERY_REMAINING_TIME_LIMIT_EXPIRED   = 0x43,
+  HID_USAGE_BATTERY_CHARGING                       = 0x44,
+  HID_USAGE_BATTERY_DISCHARGING                    = 0x45,
+  HID_USAGE_BATTERY_FULLY_CHARGED                  = 0x46,
+  HID_USAGE_BATTERY_FULLY_DISCHARGED               = 0x47,
+  HID_USAGE_BATTERY_CONDITIONING_FLAG              = 0x48,
+  HID_USAGE_BATTERY_AT_RATE_OK                     = 0x49,
+  HID_USAGE_BATTERY_SMB_ERROR_CODE                 = 0x4A,
+  HID_USAGE_BATTERY_NEED_REPLACEMENT               = 0x4B,
+  // 4C-5F Reserved
+  HID_USAGE_BATTERY_AT_RATE_TIME_TO_FULL           = 0x60,
+  HID_USAGE_BATTERY_AT_RATE_TIME_TO_EMPTY          = 0x61,
+  HID_USAGE_BATTERY_AVERAGE_CURRENT                = 0x62,
+  HID_USAGE_BATTERY_MAX_ERROR                      = 0x63,
+  HID_USAGE_BATTERY_RELATIVE_STATE_OF_CHARGE       = 0x64,
+  HID_USAGE_BATTERY_ABSOLUTE_STATE_OF_CHARGE       = 0x65,
+  HID_USAGE_BATTERY_REMAINING_CAPACITY             = 0x66,
+  HID_USAGE_BATTERY_FULL_CHARGE_CAPACITY           = 0x67,
+  HID_USAGE_BATTERY_RUN_TIME_TO_EMPTY              = 0x68,
+  HID_USAGE_BATTERY_AVERAGE_TIME_TO_EMPTY          = 0x69,
+  HID_USAGE_BATTERY_AVERAGE_TIME_TO_FULL           = 0x6A,
+  HID_USAGE_BATTERY_CYCLE_COUNT                    = 0x6B,
+  // 6C-7F Reserved
+  HID_USAGE_BATTERY_BATT_PACK_MODEL_LEVEL          = 0x80,
+  HID_USAGE_BATTERY_INTERNAL_CHARGE_CONTROLLER     = 0x81,
+  HID_USAGE_BATTERY_PRIMARY_BATTERY_SUPPORT        = 0x82,
+  HID_USAGE_BATTERY_DESIGN_CAPACITY                = 0x83,
+  HID_USAGE_BATTERY_SPECIFICATION_INFO             = 0x84,
+  HID_USAGE_BATTERY_MANUFACTURER_DATE              = 0x85,
+  HID_USAGE_BATTERY_SERIAL_NUMBER                  = 0x86,
+  HID_USAGE_BATTERY_I_MANUFACTURER_NAME            = 0x87,
+  HID_USAGE_BATTERY_I_DEVICE_NAME                  = 0x88,
+  HID_USAGE_BATTERY_I_DEVICE_CHEMISTRY             = 0x89,
+  HID_USAGE_BATTERY_MANUFACTURER_DATA              = 0x8A,
+  HID_USAGE_BATTERY_RECHARGEABLE                   = 0x8B,
+  HID_USAGE_BATTERY_WARNING_CAPACITY_LIMIT         = 0x8C,
+  HID_USAGE_BATTERY_CAPACITY_GRANULARITY_1         = 0x8D,
+  HID_USAGE_BATTERY_CAPACITY_GRANULARITY_2         = 0x8E,
+  HID_USAGE_BATTERY_I_OEMINFORMATION               = 0x8F,
+  // 90-BF Reserved
+  HID_USAGE_BATTERY_INHIBIT_CHARGE                 = 0xC0,
+  HID_USAGE_BATTERY_ENABLE_POLLING                 = 0xC1,
+  HID_USAGE_BATTERY_RESET_TO_ZERO                  = 0xC2,
+  // C3-CF Reserved
+  HID_USAGE_BATTERY_AC_PRESENT                     = 0xD0,
+  HID_USAGE_BATTERY_BATTERY_PRESENT                = 0xD1,
+  HID_USAGE_BATTERY_POWER_FAIL                     = 0xD2,
+  HID_USAGE_BATTERY_ALARM_INHIBITED                = 0xD3,
+  HID_USAGE_BATTERY_THERMISTOR_UNDER_RANGE         = 0xD4,
+  HID_USAGE_BATTERY_THERMISTOR_HOT                 = 0xD5,
+  HID_USAGE_BATTERY_THERMISTOR_COLD                = 0xD6,
+  HID_USAGE_BATTERY_THERMISTOR_OVER_RANGE          = 0xD7,
+  HID_USAGE_BATTERY_VOLTAGE_OUT_OF_RANGE           = 0xD8,
+  HID_USAGE_BATTERY_CURRENT_OUT_OF_RANGE           = 0xD9,
+  HID_USAGE_BATTERY_CURRENT_NOT_REGULATED          = 0xDA,
+  HID_USAGE_BATTERY_VOLTAGE_NOT_REGULATED          = 0xDB,
+  HID_USAGE_BATTERY_MASTER_MODE                    = 0xDC,
+  // DD-EF Reserved
+  HID_USAGE_BATTERY_CHARGER_SELECTOR_SUPPORT       = 0xF0,
+  HID_USAGE_BATTERY_CHARGER_SPEC                   = 0xF1,
+  HID_USAGE_BATTERY_LEVEL_2                        = 0xF2,
+  HID_USAGE_BATTERY_LEVEL_3                        = 0xF3
+  // F4-FF Reserved
+};
+
 /// HID Usage Table: FIDO Alliance Page (0xF1D0)
 enum {
   HID_USAGE_FIDO_U2FHID   = 0x01, // U2FHID usage for top-level collection
diff --git a/src/class/hid/hid_host.c b/src/class/hid/hid_host.c
index a44c83433..da776d04c 100644
--- a/src/class/hid/hid_host.c
+++ b/src/class/hid/hid_host.c
@@ -71,6 +71,50 @@ CFG_TUH_MEM_SECTION static hidh_epbuf_t _hidh_epbuf[CFG_TUH_HID];
 static uint8_t _hidh_default_protocol = HID_PROTOCOL_BOOT;
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tuh_hid_mount_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report_desc, uint16_t desc_len) {
+  (void) dev_addr;
+  (void) idx;
+  (void) report_desc;
+  (void) desc_len;
+}
+
+TU_ATTR_WEAK void tuh_hid_umount_cb(uint8_t dev_addr, uint8_t idx) {
+  (void) dev_addr;
+  (void) idx;
+}
+
+TU_ATTR_WEAK void tuh_hid_report_sent_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len) {
+  (void) dev_addr;
+  (void) idx;
+  (void) report;
+  (void) len;
+}
+
+TU_ATTR_WEAK void tuh_hid_get_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len) {
+  (void) dev_addr;
+  (void) idx;
+  (void) report_id;
+  (void) report_type;
+  (void) len;
+}
+
+TU_ATTR_WEAK void tuh_hid_set_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len) {
+  (void) dev_addr;
+  (void) idx;
+  (void) report_id;
+  (void) report_type;
+  (void) len;
+}
+
+TU_ATTR_WEAK void tuh_hid_set_protocol_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t protocol) {
+  (void) dev_addr;
+  (void) idx;
+  (void) protocol;
+}
+
+//--------------------------------------------------------------------+
 // Helper
 //--------------------------------------------------------------------+
 TU_ATTR_ALWAYS_INLINE static inline hidh_interface_t* get_hid_itf(uint8_t daddr, uint8_t idx) {
@@ -183,9 +227,7 @@ static void set_protocol_complete(tuh_xfer_t* xfer) {
     p_hid->protocol_mode = (uint8_t) tu_le16toh(xfer->setup->wValue);
   }
 
-  if (tuh_hid_set_protocol_complete_cb) {
-    tuh_hid_set_protocol_complete_cb(daddr, idx, p_hid->protocol_mode);
-  }
+  tuh_hid_set_protocol_complete_cb(daddr, idx, p_hid->protocol_mode);
 }
 
 void tuh_hid_set_default_protocol(uint8_t protocol) {
@@ -230,16 +272,14 @@ bool tuh_hid_set_protocol(uint8_t daddr, uint8_t idx, uint8_t protocol) {
 static void get_report_complete(tuh_xfer_t* xfer) {
   TU_LOG_DRV("HID Get Report complete\r\n");
 
-  if (tuh_hid_get_report_complete_cb) {
-    uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
-    uint8_t const idx = tuh_hid_itf_get_index(xfer->daddr, itf_num);
+  uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+  uint8_t const idx = tuh_hid_itf_get_index(xfer->daddr, itf_num);
 
-    uint8_t const report_type = tu_u16_high(xfer->setup->wValue);
+  uint8_t const report_type = tu_u16_high(xfer->setup->wValue);
     uint8_t const report_id = tu_u16_low(xfer->setup->wValue);
 
-    tuh_hid_get_report_complete_cb(xfer->daddr, idx, report_id, report_type,
-                                   (xfer->result == XFER_RESULT_SUCCESS) ? xfer->setup->wLength : 0);
-  }
+  tuh_hid_get_report_complete_cb(xfer->daddr, idx, report_id, report_type,
+                                 (xfer->result == XFER_RESULT_SUCCESS) ? xfer->setup->wLength : 0);
 }
 
 bool tuh_hid_get_report(uint8_t daddr, uint8_t idx, uint8_t report_id, uint8_t report_type, void* report, uint16_t len) {
@@ -274,16 +314,14 @@ bool tuh_hid_get_report(uint8_t daddr, uint8_t idx, uint8_t report_id, uint8_t r
 static void set_report_complete(tuh_xfer_t* xfer) {
   TU_LOG_DRV("HID Set Report complete\r\n");
 
-  if (tuh_hid_set_report_complete_cb) {
-    uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
-    uint8_t const idx = tuh_hid_itf_get_index(xfer->daddr, itf_num);
+  uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+  uint8_t const idx = tuh_hid_itf_get_index(xfer->daddr, itf_num);
 
-    uint8_t const report_type = tu_u16_high(xfer->setup->wValue);
-    uint8_t const report_id = tu_u16_low(xfer->setup->wValue);
+  uint8_t const report_type = tu_u16_high(xfer->setup->wValue);
+  uint8_t const report_id = tu_u16_low(xfer->setup->wValue);
 
-    tuh_hid_set_report_complete_cb(xfer->daddr, idx, report_id, report_type,
-                                   (xfer->result == XFER_RESULT_SUCCESS) ? xfer->setup->wLength : 0);
-  }
+  tuh_hid_set_report_complete_cb(xfer->daddr, idx, report_id, report_type,
+                                 (xfer->result == XFER_RESULT_SUCCESS) ? xfer->setup->wLength : 0);
 }
 
 bool tuh_hid_set_report(uint8_t daddr, uint8_t idx, uint8_t report_id, uint8_t report_type, void* report, uint16_t len) {
@@ -448,9 +486,7 @@ bool hidh_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t result, uint32_t
     TU_LOG3_MEM(epbuf->epin, xferred_bytes, 2);
     tuh_hid_report_received_cb(daddr, idx, epbuf->epin, (uint16_t) xferred_bytes);
   } else {
-    if (tuh_hid_report_sent_cb) {
-      tuh_hid_report_sent_cb(daddr, idx, epbuf->epout, (uint16_t) xferred_bytes);
-    }
+    tuh_hid_report_sent_cb(daddr, idx, epbuf->epout, (uint16_t) xferred_bytes);
   }
 
   return true;
@@ -461,9 +497,7 @@ void hidh_close(uint8_t daddr) {
     hidh_interface_t* p_hid = &_hidh_itf[i];
     if (p_hid->daddr == daddr) {
       TU_LOG_DRV("  HIDh close addr = %u index = %u\r\n", daddr, i);
-      if (tuh_hid_umount_cb) {
-        tuh_hid_umount_cb(daddr, i);
-      }
+      tuh_hid_umount_cb(daddr, i);
       tu_memclr(p_hid, sizeof(hidh_interface_t));
     }
   }
@@ -625,7 +659,7 @@ static void config_driver_mount_complete(uint8_t daddr, uint8_t idx, uint8_t con
   p_hid->mounted = true;
 
   // enumeration is complete
-  if (tuh_hid_mount_cb) tuh_hid_mount_cb(daddr, idx, desc_report, desc_len);
+  tuh_hid_mount_cb(daddr, idx, desc_report, desc_len);
 
   // notify usbh that driver enumeration is complete
   usbh_driver_set_config_complete(daddr, p_hid->itf_num);
diff --git a/src/class/hid/hid_host.h b/src/class/hid/hid_host.h
index 9681c704b..032827af1 100644
--- a/src/class/hid/hid_host.h
+++ b/src/class/hid/hid_host.h
@@ -145,28 +145,28 @@ bool tuh_hid_send_report(uint8_t dev_addr, uint8_t idx, uint8_t report_id, const
 // can be used to parse common/simple enough descriptor.
 // Note: if report descriptor length > CFG_TUH_ENUMERATION_BUFSIZE, it will be skipped
 // therefore report_desc = NULL, desc_len = 0
-TU_ATTR_WEAK void tuh_hid_mount_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report_desc, uint16_t desc_len);
+void tuh_hid_mount_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report_desc, uint16_t desc_len);
 
 // Invoked when device with hid interface is un-mounted
-TU_ATTR_WEAK void tuh_hid_umount_cb(uint8_t dev_addr, uint8_t idx);
+void tuh_hid_umount_cb(uint8_t dev_addr, uint8_t idx);
 
 // Invoked when received report from device via interrupt endpoint
 // Note: if there is report ID (composite), it is 1st byte of report
 void tuh_hid_report_received_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len);
 
 // Invoked when sent report to device successfully via interrupt endpoint
-TU_ATTR_WEAK void tuh_hid_report_sent_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len);
+void tuh_hid_report_sent_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len);
 
 // Invoked when Get Report to device via either control endpoint
 // len = 0 indicate there is error in the transfer e.g stalled response
-TU_ATTR_WEAK void tuh_hid_get_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len);
+void tuh_hid_get_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len);
 
 // Invoked when Sent Report to device via either control endpoint
 // len = 0 indicate there is error in the transfer e.g stalled response
-TU_ATTR_WEAK void tuh_hid_set_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len);
+void tuh_hid_set_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len);
 
 // Invoked when Set Protocol request is complete
-TU_ATTR_WEAK void tuh_hid_set_protocol_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t protocol);
+void tuh_hid_set_protocol_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t protocol);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index 0bbb3caf4..7dac7c4a5 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -107,6 +107,14 @@ static void _prep_out_transaction(uint8_t idx) {
   }
 }
 
+
+//--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_midi_rx_cb(uint8_t itf) {
+  (void) itf;
+}
+
 //--------------------------------------------------------------------+
 // READ API
 //--------------------------------------------------------------------+
@@ -528,9 +536,7 @@ bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32
     tu_fifo_write_n(&p_midi->rx_ff, _midid_epbuf[idx].epout, (uint16_t)xferred_bytes);
 
     // invoke receive callback if available
-    if (tud_midi_rx_cb) {
-      tud_midi_rx_cb(idx);
-    }
+    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,
diff --git a/src/class/midi/midi_device.h b/src/class/midi/midi_device.h
index 3e89cc0a3..c2c6e9859 100644
--- a/src/class/midi/midi_device.h
+++ b/src/class/midi/midi_device.h
@@ -116,9 +116,9 @@ static inline bool tud_midi_receive(uint8_t packet[4])
 }
 
 //--------------------------------------------------------------------+
-// Application Callback API (weak is optional)
+// Application Callback API (optional)
 //--------------------------------------------------------------------+
-TU_ATTR_WEAK void tud_midi_rx_cb(uint8_t itf);
+void tud_midi_rx_cb(uint8_t itf);
 
 //--------------------------------------------------------------------+
 // Inline Functions
diff --git a/src/class/msc/msc_device.c b/src/class/msc/msc_device.c
index a32014c2d..b0eafd5da 100644
--- a/src/class/msc/msc_device.c
+++ b/src/class/msc/msc_device.c
@@ -224,6 +224,53 @@ static bool proc_stage_status(mscd_interface_t *p_msc) {
 }
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_msc_read10_complete_cb(uint8_t lun) {
+  (void) lun;
+}
+
+TU_ATTR_WEAK void tud_msc_write10_complete_cb(uint8_t lun) {
+  (void) lun;
+}
+
+TU_ATTR_WEAK void tud_msc_scsi_complete_cb(uint8_t lun, uint8_t const scsi_cmd[16]) {
+  (void) lun;
+  (void) scsi_cmd;
+}
+
+TU_ATTR_WEAK uint8_t tud_msc_get_maxlun_cb(void) {
+  return 1;
+}
+
+TU_ATTR_WEAK bool tud_msc_start_stop_cb(uint8_t lun, uint8_t power_condition, bool start, bool load_eject) {
+  (void) lun;
+  (void) power_condition;
+  (void) start;
+  (void) load_eject;
+  return true;
+}
+
+TU_ATTR_WEAK bool tud_msc_prevent_allow_medium_removal_cb(uint8_t lun, uint8_t prohibit_removal, uint8_t control) {
+  (void) lun;
+  (void) prohibit_removal;
+  (void) control;
+  return true;
+}
+
+TU_ATTR_WEAK int32_t tud_msc_request_sense_cb(uint8_t lun, void* buffer, uint16_t bufsize) {
+  (void) lun;
+  (void) buffer;
+  (void) bufsize;
+  return sizeof(scsi_sense_fixed_resp_t);
+}
+
+TU_ATTR_WEAK bool tud_msc_is_writable_cb(uint8_t lun) {
+  (void) lun;
+  return true;
+}
+
+//--------------------------------------------------------------------+
 // Debug
 //--------------------------------------------------------------------+
 #if CFG_TUSB_DEBUG >= CFG_TUD_MSC_LOG_LEVEL
@@ -403,10 +450,7 @@ bool mscd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t
       TU_LOG_DRV("  MSC Get Max Lun\r\n");
       TU_VERIFY(request->wValue == 0 && request->wLength == 1);
 
-      uint8_t maxlun = 1;
-      if (tud_msc_get_maxlun_cb) {
-        maxlun = tud_msc_get_maxlun_cb();
-      }
+      uint8_t maxlun = tud_msc_get_maxlun_cb();
       TU_VERIFY(maxlun);
       maxlun--; // MAX LUN is minus 1 by specs
       tud_control_xfer(rhport, request, &maxlun, 1);
@@ -584,21 +628,15 @@ bool mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
         // if complete_cb() is invoked after queuing the status.
         switch (p_cbw->command[0]) {
           case SCSI_CMD_READ_10:
-            if (tud_msc_read10_complete_cb) {
-              tud_msc_read10_complete_cb(p_cbw->lun);
-            }
+            tud_msc_read10_complete_cb(p_cbw->lun);
             break;
 
           case SCSI_CMD_WRITE_10:
-            if (tud_msc_write10_complete_cb) {
-              tud_msc_write10_complete_cb(p_cbw->lun);
-            }
+            tud_msc_write10_complete_cb(p_cbw->lun);
             break;
 
           default:
-            if (tud_msc_scsi_complete_cb) {
-              tud_msc_scsi_complete_cb(p_cbw->lun, p_cbw->command);
-            }
+            tud_msc_scsi_complete_cb(p_cbw->lun, p_cbw->command);
             break;
         }
 
@@ -648,16 +686,14 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
     case SCSI_CMD_START_STOP_UNIT:
       resplen = 0;
 
-      if (tud_msc_start_stop_cb) {
-        scsi_start_stop_unit_t const* start_stop = (scsi_start_stop_unit_t const*)scsi_cmd;
-        if (!tud_msc_start_stop_cb(lun, start_stop->power_condition, start_stop->start, start_stop->load_eject)) {
-          // Failed status response
-          resplen = -1;
+      scsi_start_stop_unit_t const* start_stop = (scsi_start_stop_unit_t const*)scsi_cmd;
+      if (!tud_msc_start_stop_cb(lun, start_stop->power_condition, start_stop->start, start_stop->load_eject)) {
+        // Failed status response
+        resplen = -1;
 
-          // set default sense if not set by callback
-          if (p_msc->sense_key == 0) {
-            set_sense_medium_not_present(lun);
-          }
+        // set default sense if not set by callback
+        if (p_msc->sense_key == 0) {
+          set_sense_medium_not_present(lun);
         }
       }
       break;
@@ -665,16 +701,14 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
     case SCSI_CMD_PREVENT_ALLOW_MEDIUM_REMOVAL:
       resplen = 0;
 
-      if (tud_msc_prevent_allow_medium_removal_cb) {
-        scsi_prevent_allow_medium_removal_t const* prevent_allow = (scsi_prevent_allow_medium_removal_t const*)scsi_cmd;
-        if (!tud_msc_prevent_allow_medium_removal_cb(lun, prevent_allow->prohibit_removal, prevent_allow->control)) {
-          // Failed status response
-          resplen = -1;
+      scsi_prevent_allow_medium_removal_t const* prevent_allow = (scsi_prevent_allow_medium_removal_t const*)scsi_cmd;
+      if (!tud_msc_prevent_allow_medium_removal_cb(lun, prevent_allow->prohibit_removal, prevent_allow->control)) {
+        // Failed status response
+        resplen = -1;
 
-          // set default sense if not set by callback
-          if (p_msc->sense_key == 0) {
-            set_sense_medium_not_present(lun);
-          }
+        // set default sense if not set by callback
+        if (p_msc->sense_key == 0) {
+          set_sense_medium_not_present(lun);
         }
       }
       break;
@@ -767,10 +801,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
         .block_descriptor_len = 0 // no block descriptor are included
       };
 
-      bool writable = true;
-      if (tud_msc_is_writable_cb) {
-        writable = tud_msc_is_writable_cb(lun);
-      }
+      bool writable = tud_msc_is_writable_cb(lun);
 
       mode_resp.write_protected = !writable;
 
@@ -794,9 +825,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
       TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &sense_rsp, (size_t) resplen));
 
       // request sense callback could overwrite the sense data
-      if (tud_msc_request_sense_cb) {
-        resplen = tud_msc_request_sense_cb(lun, buffer, (uint16_t)bufsize);
-      }
+      resplen = tud_msc_request_sense_cb(lun, buffer, (uint16_t)bufsize);
 
       // Clear sense data after copy
       tud_msc_set_sense(lun, 0, 0, 0);
@@ -854,11 +883,7 @@ static void proc_read_io_data(mscd_interface_t* p_msc, int32_t nbytes) {
 
 static void proc_write10_cmd(mscd_interface_t* p_msc) {
   msc_cbw_t const* p_cbw = &p_msc->cbw;
-  bool writable = true;
-
-  if (tud_msc_is_writable_cb) {
-    writable = tud_msc_is_writable_cb(p_cbw->lun);
-  }
+  bool writable = tud_msc_is_writable_cb(p_cbw->lun);
 
   if (!writable) {
     // Not writable, complete this SCSI op with error
diff --git a/src/class/msc/msc_device.h b/src/class/msc/msc_device.h
index 144b74f71..7d898e988 100644
--- a/src/class/msc/msc_device.h
+++ b/src/class/msc/msc_device.h
@@ -128,30 +128,30 @@ int32_t tud_msc_scsi_cb (uint8_t lun, uint8_t const scsi_cmd[16], void* buffer,
 /*------------- Optional callbacks -------------*/
 
 // Invoked when received GET_MAX_LUN request, required for multiple LUNs implementation
-TU_ATTR_WEAK uint8_t tud_msc_get_maxlun_cb(void);
+uint8_t tud_msc_get_maxlun_cb(void);
 
 // Invoked when received Start Stop Unit command
 // - Start = 0 : stopped power mode, if load_eject = 1 : unload disk storage
 // - Start = 1 : active mode, if load_eject = 1 : load disk storage
-TU_ATTR_WEAK bool tud_msc_start_stop_cb(uint8_t lun, uint8_t power_condition, bool start, bool load_eject);
+bool tud_msc_start_stop_cb(uint8_t lun, uint8_t power_condition, bool start, bool load_eject);
 
 //Invoked when we receive the Prevent / Allow Medium Removal command
-TU_ATTR_WEAK bool tud_msc_prevent_allow_medium_removal_cb(uint8_t lun, uint8_t prohibit_removal, uint8_t control);
+bool tud_msc_prevent_allow_medium_removal_cb(uint8_t lun, uint8_t prohibit_removal, uint8_t control);
 
 // Invoked when received REQUEST_SENSE
-TU_ATTR_WEAK int32_t tud_msc_request_sense_cb(uint8_t lun, void* buffer, uint16_t bufsize);
+int32_t tud_msc_request_sense_cb(uint8_t lun, void* buffer, uint16_t bufsize);
 
 // Invoked when Read10 command is complete
-TU_ATTR_WEAK void tud_msc_read10_complete_cb(uint8_t lun);
+void tud_msc_read10_complete_cb(uint8_t lun);
 
 // Invoke when Write10 command is complete, can be used to flush flash caching
-TU_ATTR_WEAK void tud_msc_write10_complete_cb(uint8_t lun);
+void tud_msc_write10_complete_cb(uint8_t lun);
 
 // Invoked when command in tud_msc_scsi_cb is complete
-TU_ATTR_WEAK void tud_msc_scsi_complete_cb(uint8_t lun, uint8_t const scsi_cmd[16]);
+void tud_msc_scsi_complete_cb(uint8_t lun, uint8_t const scsi_cmd[16]);
 
 // Invoked to check if device is writable as part of SCSI WRITE10
-TU_ATTR_WEAK bool tud_msc_is_writable_cb(uint8_t lun);
+bool tud_msc_is_writable_cb(uint8_t lun);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/msc/msc_host.c b/src/class/msc/msc_host.c
index ef0635bbe..eb69ae400 100644
--- a/src/class/msc/msc_host.c
+++ b/src/class/msc/msc_host.c
@@ -88,6 +88,17 @@ TU_ATTR_ALWAYS_INLINE static inline msch_epbuf_t* get_epbuf(uint8_t daddr) {
 }
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tuh_msc_mount_cb(uint8_t dev_addr) {
+  (void) dev_addr;
+}
+
+TU_ATTR_WEAK void tuh_msc_umount_cb(uint8_t dev_addr) {
+  (void) dev_addr;
+}
+
+//--------------------------------------------------------------------+
 // PUBLIC API
 //--------------------------------------------------------------------+
 uint8_t tuh_msc_get_maxlun(uint8_t dev_addr) {
@@ -304,9 +315,7 @@ void msch_close(uint8_t dev_addr) {
 
   // invoke Application Callback
   if (p_msc->mounted) {
-    if (tuh_msc_umount_cb) {
-      tuh_msc_umount_cb(dev_addr);
-    }
+    tuh_msc_umount_cb(dev_addr);
   }
 
   tu_memclr(p_msc, sizeof(msch_interface_t));
@@ -497,9 +506,7 @@ static bool config_read_capacity_complete(uint8_t dev_addr, tuh_msc_complete_dat
 
   // Mark enumeration is complete
   p_msc->mounted = true;
-  if (tuh_msc_mount_cb) {
-    tuh_msc_mount_cb(dev_addr);
-  }
+  tuh_msc_mount_cb(dev_addr);
 
   // notify usbh that driver enumeration is complete
   usbh_driver_set_config_complete(dev_addr, p_msc->itf_num);
diff --git a/src/class/msc/msc_host.h b/src/class/msc/msc_host.h
index 09d777066..b5fd55547 100644
--- a/src/class/msc/msc_host.h
+++ b/src/class/msc/msc_host.h
@@ -109,10 +109,10 @@ bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_r
 //------------- Application Callback -------------//
 
 // Invoked when a device with MassStorage interface is mounted
-TU_ATTR_WEAK void tuh_msc_mount_cb(uint8_t dev_addr);
+void tuh_msc_mount_cb(uint8_t dev_addr);
 
 // Invoked when a device with MassStorage interface is unmounted
-TU_ATTR_WEAK void tuh_msc_umount_cb(uint8_t dev_addr);
+void tuh_msc_umount_cb(uint8_t dev_addr);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/usbtmc/usbtmc_device.c b/src/class/usbtmc/usbtmc_device.c
index 7ec939b64..3f6bedd4c 100644
--- a/src/class/usbtmc/usbtmc_device.c
+++ b/src/class/usbtmc/usbtmc_device.c
@@ -159,6 +159,25 @@ TU_VERIFY_STATIC(USBTMCD_BUFFER_SIZE >= 32u, "USBTMC dev buffer size too small")
 static bool handle_devMsgOutStart(uint8_t rhport, void *data, size_t len);
 static bool handle_devMsgOut(uint8_t rhport, void *data, size_t len, size_t packetLen);
 
+
+// USBTMC Device Callbacks weak implementations
+TU_ATTR_WEAK bool tud_usbtmc_notification_complete_cb(void) {
+  return true;
+}
+
+TU_ATTR_WEAK bool tud_usbtmc_indicator_pulse_cb(tusb_control_request_t const * msg, uint8_t *tmcResult) {
+  (void) msg;
+  (void) tmcResult;
+  return true;
+}
+
+#if (CFG_TUD_USBTMC_ENABLE_488)
+TU_ATTR_WEAK bool tud_usbtmc_msg_trigger_cb(usbtmc_msg_generic_t* msg) {
+  (void) msg;
+  return true;
+}
+#endif
+
 #ifndef NDEBUG
 tu_static uint8_t termChar;
 #endif
@@ -262,16 +281,10 @@ void usbtmcd_init_cb(void) {
   usbtmc_state.capabilities = tud_usbtmc_get_capabilities_cb();
 #ifndef NDEBUG
   #if CFG_TUD_USBTMC_ENABLE_488
-  if (usbtmc_state.capabilities->bmIntfcCapabilities488.supportsTrigger) {
-    TU_ASSERT(&tud_usbtmc_msg_trigger_cb != NULL, );
-  }
   // Per USB488 spec: table 8
   TU_ASSERT(!usbtmc_state.capabilities->bmIntfcCapabilities.listenOnly, );
   TU_ASSERT(!usbtmc_state.capabilities->bmIntfcCapabilities.talkOnly, );
   #endif
-  if (usbtmc_state.capabilities->bmIntfcCapabilities.supportsIndicatorPulse) {
-    TU_ASSERT(&tud_usbtmc_indicator_pulse_cb != NULL, );
-  }
 #endif
 
   usbtmcLock = osal_mutex_create(&usbtmcLockBuffer);
@@ -587,9 +600,7 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
         TU_ASSERT(false);
     }
   } else if (ep_addr == usbtmc_state.ep_int_in) {
-    if (tud_usbtmc_notification_complete_cb) {
-      TU_VERIFY(tud_usbtmc_notification_complete_cb());
-    }
+    TU_VERIFY(tud_usbtmc_notification_complete_cb());
     return true;
   }
   return false;
diff --git a/src/class/usbtmc/usbtmc_device.h b/src/class/usbtmc/usbtmc_device.h
index b85ef12b5..235f1276e 100644
--- a/src/class/usbtmc/usbtmc_device.h
+++ b/src/class/usbtmc/usbtmc_device.h
@@ -75,15 +75,14 @@ bool tud_usbtmc_check_clear_cb(usbtmc_get_clear_status_rsp_t *rsp);
 
 // The interrupt-IN endpoint buffer was transmitted to the host. Use
 // tud_usbtmc_transmit_notification_data to send another notification.
-TU_ATTR_WEAK bool tud_usbtmc_notification_complete_cb(void);
+bool tud_usbtmc_notification_complete_cb(void);
 
 // Indicator pulse should be 0.5 to 1.0 seconds long
-TU_ATTR_WEAK bool tud_usbtmc_indicator_pulse_cb(tusb_control_request_t const * msg, uint8_t *tmcResult);
+bool tud_usbtmc_indicator_pulse_cb(tusb_control_request_t const * msg, uint8_t *tmcResult);
 
 #if (CFG_TUD_USBTMC_ENABLE_488)
 uint8_t tud_usbtmc_get_stb_cb(uint8_t *tmcResult);
-TU_ATTR_WEAK bool tud_usbtmc_msg_trigger_cb(usbtmc_msg_generic_t* msg);
-//TU_ATTR_WEAK bool tud_usbtmc_app_go_to_local_cb();
+bool tud_usbtmc_msg_trigger_cb(usbtmc_msg_generic_t* msg);
 #endif
 
 // Called from app
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index b0332b0fe..27724b194 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -67,6 +67,20 @@ typedef struct {
 
 CFG_TUD_MEM_SECTION static vendord_epbuf_t _vendord_epbuf[CFG_TUD_VENDOR];
 
+//--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize) {
+  (void) itf;
+  (void) buffer;
+  (void) bufsize;
+}
+
+TU_ATTR_WEAK void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes) {
+  (void) itf;
+  (void) sent_bytes;
+}
+
 //--------------------------------------------------------------------
 // Application API
 //--------------------------------------------------------------------
@@ -259,16 +273,12 @@ bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     tu_edpt_stream_read_xfer_complete(&p_vendor->rx.stream, xferred_bytes);
 
     // Invoked callback if any
-    if (tud_vendor_rx_cb) {
-      tud_vendor_rx_cb(itf, p_epbuf->epout, (uint16_t) xferred_bytes);
-    }
+    tud_vendor_rx_cb(itf, p_epbuf->epout, (uint16_t) xferred_bytes);
 
     tu_edpt_stream_read_xfer(rhport, &p_vendor->rx.stream);
   } else if ( ep_addr == p_vendor->tx.stream.ep_addr ) {
     // Send complete
-    if (tud_vendor_tx_cb) {
-      tud_vendor_tx_cb(itf, (uint16_t) xferred_bytes);
-    }
+    tud_vendor_tx_cb(itf, (uint16_t) xferred_bytes);
 
     #if CFG_TUD_VENDOR_TX_BUFSIZE > 0
     // try to send more if possible
diff --git a/src/class/vendor/vendor_device.h b/src/class/vendor/vendor_device.h
index 149ae2d56..5fe4fc9ff 100644
--- a/src/class/vendor/vendor_device.h
+++ b/src/class/vendor/vendor_device.h
@@ -119,9 +119,9 @@ TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_available(void) {
 //--------------------------------------------------------------------+
 
 // Invoked when received new data
-TU_ATTR_WEAK void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize);
+void tud_vendor_rx_cb(uint8_t itf, uint8_t const* buffer, uint16_t bufsize);
 // Invoked when last rx transfer finished
-TU_ATTR_WEAK void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes);
+void tud_vendor_tx_cb(uint8_t itf, uint32_t sent_bytes);
 
 //--------------------------------------------------------------------+
 // Inline Functions
diff --git a/src/class/video/video_device.c b/src/class/video/video_device.c
index 3124d5596..5c00cc358 100644
--- a/src/class/video/video_device.c
+++ b/src/class/video/video_device.c
@@ -193,6 +193,28 @@ static char const* const tu_str_video_vs_control_selector[] = {
 #endif
 
 //--------------------------------------------------------------------+
+// Weak stubs: invoked if no strong implementation is available
+//--------------------------------------------------------------------+
+TU_ATTR_WEAK void tud_video_frame_xfer_complete_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx) {
+  (void) ctl_idx;
+  (void) stm_idx;
+}
+
+TU_ATTR_WEAK int tud_video_power_mode_cb(uint_fast8_t ctl_idx, uint8_t power_mod) {
+  (void) ctl_idx;
+  (void) power_mod;
+  return VIDEO_ERROR_NONE;
+}
+
+TU_ATTR_WEAK int tud_video_commit_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx,
+                                    video_probe_and_commit_control_t const *parameters) {
+  (void) ctl_idx;
+  (void) stm_idx;
+  (void) parameters;
+  return VIDEO_ERROR_NONE;
+}
+
+//--------------------------------------------------------------------+
 //
 //--------------------------------------------------------------------+
 
@@ -902,7 +924,7 @@ static int handle_video_ctl_cs_req(uint8_t rhport, uint8_t stage,
             TU_VERIFY(1 == request->wLength, VIDEO_ERROR_UNKNOWN);
             TU_VERIFY(tud_control_xfer(rhport, request, &self->power_mode, sizeof(self->power_mode)), VIDEO_ERROR_UNKNOWN);
           } else if (stage == CONTROL_STAGE_DATA) {
-            if (tud_video_power_mode_cb) return tud_video_power_mode_cb(ctl_idx, self->power_mode);
+            return tud_video_power_mode_cb(ctl_idx, self->power_mode);
           }
           return VIDEO_ERROR_NONE;
 
@@ -1104,10 +1126,7 @@ static int handle_video_stm_cs_req(uint8_t rhport, uint8_t stage,
             TU_VERIFY(_update_streaming_parameters(stm, param), VIDEO_ERROR_INVALID_VALUE_WITHIN_RANGE);
             /* Set the negotiated value */
             stm->max_payload_transfer_size = param->dwMaxPayloadTransferSize;
-            int ret = VIDEO_ERROR_NONE;
-            if (tud_video_commit_cb) {
-              ret = tud_video_commit_cb(stm->index_vc, stm->index_vs, param);
-            }
+            int ret = tud_video_commit_cb(stm->index_vc, stm->index_vs, param);
             if (VIDEO_ERROR_NONE == ret) {
               stm->state   = VS_STATE_COMMITTED;
               stm->buffer  = NULL;
@@ -1419,9 +1438,7 @@ bool videod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
     stm->buffer  = NULL;
     stm->bufsize = 0;
     stm->offset  = 0;
-    if (tud_video_frame_xfer_complete_cb) {
-      tud_video_frame_xfer_complete_cb(stm->index_vc, stm->index_vs);
-    }
+    tud_video_frame_xfer_complete_cb(stm->index_vc, stm->index_vs);
   }
   return true;
 }
diff --git a/src/class/video/video_device.h b/src/class/video/video_device.h
index 648a221d5..2b41c3bfe 100644
--- a/src/class/video/video_device.h
+++ b/src/class/video/video_device.h
@@ -61,7 +61,7 @@ bool tud_video_n_frame_xfer(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, void *bu
  *
  * @param[in] ctl_idx    Destination control interface index
  * @param[in] stm_idx    Destination streaming interface index */
-TU_ATTR_WEAK void tud_video_frame_xfer_complete_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx);
+void tud_video_frame_xfer_complete_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx);
 
 //--------------------------------------------------------------------+
 // Application Callback API (weak is optional)
@@ -72,7 +72,7 @@ TU_ATTR_WEAK void tud_video_frame_xfer_complete_cb(uint_fast8_t ctl_idx, uint_fa
  * @param[in] ctl_idx    Destination control interface index
  * @param[in] stm_idx    Destination streaming interface index
  * @return video_error_code_t */
-TU_ATTR_WEAK int tud_video_power_mode_cb(uint_fast8_t ctl_idx, uint8_t power_mod);
+int tud_video_power_mode_cb(uint_fast8_t ctl_idx, uint8_t power_mod);
 
 /** Invoked when VS_COMMIT_CONTROL(SET_CUR) request received
  *
@@ -80,7 +80,7 @@ TU_ATTR_WEAK int tud_video_power_mode_cb(uint_fast8_t ctl_idx, uint8_t power_mod
  * @param[in] stm_idx     Destination streaming interface index
  * @param[in] parameters  Video streaming parameters
  * @return video_error_code_t */
-TU_ATTR_WEAK int tud_video_commit_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx,
+int tud_video_commit_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx,
                                      video_probe_and_commit_control_t const *parameters);
 
 //--------------------------------------------------------------------+