Merge remote-tracking branch 'upstream/master' into pr/1702

1 files changed, 548 insertions, 306 deletions

diff --git a/src/class/audio/audio_device.c b/src/class/audio/audio_device.c
index 4681e1ddb..f4e7de0c8 100644
--- a/src/class/audio/audio_device.c
+++ b/src/class/audio/audio_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Reinhard Panhuber, Jerzy Kasenberg
@@ -66,51 +66,41 @@
 
 // Use ring buffer if it's available, some MCUs need extra RAM requirements
 #ifndef TUD_AUDIO_PREFER_RING_BUFFER
-#if CFG_TUSB_MCU == OPT_MCU_LPC43XX || CFG_TUSB_MCU == OPT_MCU_LPC18XX || CFG_TUSB_MCU == OPT_MCU_MIMXRT
-#define TUD_AUDIO_PREFER_RING_BUFFER 0
-#else
-#define TUD_AUDIO_PREFER_RING_BUFFER 1
-#endif
+  #if CFG_TUSB_MCU == OPT_MCU_LPC43XX || CFG_TUSB_MCU == OPT_MCU_LPC18XX || CFG_TUSB_MCU == OPT_MCU_MIMXRT1XXX
+    #define TUD_AUDIO_PREFER_RING_BUFFER 0
+  #else
+    #define TUD_AUDIO_PREFER_RING_BUFFER 1
+  #endif
 #endif
 
 // Linear buffer in case target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer
 // is available or driver is would need to be changed dramatically
 
-// Only STM32 synopsys and dcd_transdimension use non-linear buffer for now
-// Synopsys detection copied from dcd_synopsys.c (refactor later on)
-#if defined (STM32F105x8) || defined (STM32F105xB) || defined (STM32F105xC) || \
-    defined (STM32F107xB) || defined (STM32F107xC)
-#define STM32F1_SYNOPSYS
-#endif
-
-#if defined (STM32L475xx) || defined (STM32L476xx) ||                          \
-    defined (STM32L485xx) || defined (STM32L486xx) || defined (STM32L496xx) || \
-    defined (STM32L4R5xx) || defined (STM32L4R7xx) || defined (STM32L4R9xx) || \
-    defined (STM32L4S5xx) || defined (STM32L4S7xx) || defined (STM32L4S9xx)
-#define STM32L4_SYNOPSYS
-#endif
-
-#if (CFG_TUSB_MCU == OPT_MCU_STM32F1 && defined(STM32F1_SYNOPSYS)) || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F2                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F4                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F7                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32H7                               || \
-    (CFG_TUSB_MCU == OPT_MCU_STM32L4 && defined(STM32L4_SYNOPSYS)) || \
-    CFG_TUSB_MCU == OPT_MCU_RX63X                                 || \
-    CFG_TUSB_MCU == OPT_MCU_RX65X                                 || \
-    CFG_TUSB_MCU == OPT_MCU_RX72N                                 || \
-    CFG_TUSB_MCU == OPT_MCU_GD32VF103                             || \
-    CFG_TUSB_MCU == OPT_MCU_LPC18XX                               || \
-    CFG_TUSB_MCU == OPT_MCU_LPC43XX                               || \
-    CFG_TUSB_MCU == OPT_MCU_MIMXRT                                || \
+// Only STM32 and dcd_transdimension use non-linear buffer for now
+// dwc2 except esp32sx (since it may use dcd_esp32sx)
+#if (defined(TUP_USBIP_DWC2) && !TU_CHECK_MCU(OPT_MCU_ESP32S2, OPT_MCU_ESP32S3)) || \
+    defined(TUP_USBIP_FSDEV)          || \
+    CFG_TUSB_MCU == OPT_MCU_RX63X     || \
+    CFG_TUSB_MCU == OPT_MCU_RX65X     || \
+    CFG_TUSB_MCU == OPT_MCU_RX72N     || \
+    CFG_TUSB_MCU == OPT_MCU_LPC18XX   || \
+    CFG_TUSB_MCU == OPT_MCU_LPC43XX   || \
+    CFG_TUSB_MCU == OPT_MCU_MIMXRT1XXX    || \
     CFG_TUSB_MCU == OPT_MCU_MSP432E4
-#if TUD_AUDIO_PREFER_RING_BUFFER
-#define  USE_LINEAR_BUFFER     0
+  #if TUD_AUDIO_PREFER_RING_BUFFER
+    #define  USE_LINEAR_BUFFER     0
+  #else
+    #define  USE_LINEAR_BUFFER     1
+  #endif
 #else
-#define  USE_LINEAR_BUFFER     1
+  #define  USE_LINEAR_BUFFER     1
 #endif
+
+// Temporarily put the check here
+#if defined(TUP_USBIP_FSDEV) || defined(TUP_USBIP_DWC2)
+  #define  USE_ISO_EP_ALLOCATION   1
 #else
-#define  USE_LINEAR_BUFFER     1
+  #define  USE_ISO_EP_ALLOCATION   0
 #endif
 
 // Declaration of buffers
@@ -120,145 +110,173 @@
 #error Maximum number of audio functions restricted to three!
 #endif
 
-// EP IN software buffers and mutexes
-#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
-#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_1;                                                             // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif // CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_2;                                                             // No need for read mutex as only USB driver reads from FIFO
+// Put sw_buf in USB section only if necessary
+#if USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_ENCODING
+#define IN_SW_BUF_MEM_SECTION
+#else
+#define IN_SW_BUF_MEM_SECTION CFG_TUD_MEM_SECTION
 #endif
-#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_3;                                                             // No need for read mutex as only USB driver reads from FIFO
+#if USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING
+#define OUT_SW_BUF_MEM_SECTION
+#else
+#define OUT_SW_BUF_MEM_SECTION CFG_TUD_MEM_SECTION
 #endif
-#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+
+// EP IN software buffers and mutexes
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+  #if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+    IN_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_1; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+    IN_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_2; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+    IN_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_3; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
 #endif // CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
 
 // Linear buffer TX in case:
 // - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
 // - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_ENCODING)
-#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX];
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX];
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
 
 // EP OUT software buffers and mutexes
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
-#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_1;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_2;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_3;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+  #if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+    OUT_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_1; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+    OUT_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_2; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+    OUT_SW_BUF_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_3; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
 
 // Linear buffer RX in case:
 // - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
 // - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
-#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX];
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
+    CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX];
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
 
 // Control buffers
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_1[CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ];
+CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_1[CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ];
+
 #if CFG_TUD_AUDIO > 1
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_2[CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ];
+CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_2[CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ];
 #endif
+
 #if CFG_TUD_AUDIO > 2
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_3[CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ];
+CFG_TUD_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_3[CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ];
 #endif
 
 // Active alternate setting of interfaces
 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
 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
 uint8_t alt_setting_3[CFG_TUD_AUDIO_FUNC_3_N_AS_INT];
 #endif
 
 // Software encoding/decoding support FIFOs
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
-#if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
-#if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
 #endif
 
 typedef struct
@@ -306,7 +324,7 @@ typedef struct
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
   struct {
-    uint32_t value;       // Feedback value for asynchronous mode (in 16.16 format).
+    CFG_TUSB_MEM_ALIGN uint32_t value;  // Feedback value for asynchronous mode (in 16.16 format).
     uint32_t min_value;   // min value according to UAC2 FMT-2.0 section 2.3.1.1.
     uint32_t max_value;   // max value according to UAC2 FMT-2.0 section 2.3.1.1.
 
@@ -358,14 +376,21 @@ typedef struct
 #endif
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+  uint32_t sample_rate_tx;
+  uint16_t packet_sz_tx[3];
+  uint8_t bclock_id_tx;
+  uint8_t interval_tx;
+#endif
+
   // Encoding parameters - parameters are set when alternate AS interface is set by host
-#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && (CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL)
   audio_format_type_t format_type_tx;
   uint8_t n_channels_tx;
+  uint8_t n_bytes_per_sampe_tx;
 
 #if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
   audio_data_format_type_I_t format_type_I_tx;
-  uint8_t n_bytes_per_sampe_tx;
   uint8_t n_channels_per_ff_tx;
   uint8_t n_ff_used_tx;
 #endif
@@ -410,7 +435,7 @@ typedef struct
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
-CFG_TUSB_MEM_SECTION audiod_function_t _audiod_fct[CFG_TUD_AUDIO];
+CFG_TUD_MEM_SECTION audiod_function_t _audiod_fct[CFG_TUD_AUDIO];
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
 static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t n_bytes_received);
@@ -438,7 +463,7 @@ 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);
 static uint8_t audiod_get_audio_fct_idx(audiod_function_t * audio);
 
-#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+#if (CFG_TUD_AUDIO_ENABLE_EP_IN && (CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL || CFG_TUD_AUDIO_ENABLE_ENCODING)) || (CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING)
 static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const * p_desc, uint8_t const * p_desc_end, uint8_t const as_itf);
 
 static inline uint8_t tu_desc_subtype(void const* desc)
@@ -447,6 +472,11 @@ static inline uint8_t tu_desc_subtype(void const* desc)
 }
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+static bool audiod_calc_tx_packet_sz(audiod_function_t* audio);
+static uint16_t audiod_tx_packet_size(const uint16_t* norminal_size, uint16_t data_count, uint16_t fifo_depth, uint16_t max_size);
+#endif
+
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 static bool set_fb_params_freq(audiod_function_t* audio, uint32_t sample_freq, uint32_t mclk_freq);
 #endif
@@ -625,73 +655,55 @@ static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t
 // Decoding according to 2.3.1.5 Audio Streams
 
 // Helper function
-static inline uint8_t * audiod_interleaved_copy_bytes_fast_decode(uint16_t const nBytesToCopy, void * dst, uint8_t * dst_end, uint8_t * src, uint8_t const n_ff_used)
+static inline void * audiod_interleaved_copy_bytes_fast_decode(uint16_t const nBytesPerSample, void * dst, const void * dst_end, void * src, uint8_t const n_ff_used)
 {
+  // Due to one FIFO contains 2 channels, data always aligned to (nBytesPerSample * 2)
+  uint16_t * dst16 = dst;
+  uint16_t * src16 = src;
+  const uint16_t * dst_end16 = dst_end;
+  uint32_t * dst32 = dst;
+  uint32_t * src32 = src;
+  const uint32_t * dst_end32 = dst_end;
 
-  // This function is an optimized version of
-  //  while((uint8_t *)dst < dst_end)
-  //  {
-  //    memcpy(dst, src, nBytesToCopy);
-  //    dst = (uint8_t *)dst + nBytesToCopy;
-  //    src += nBytesToCopy * n_ff_used;
-  //  }
-
-  // Optimize for fast half word copies
-  typedef struct{
-    uint16_t val;
-  } __attribute((__packed__)) unaligned_uint16_t;
-
-  // Optimize for fast word copies
-  typedef struct{
-    uint32_t val;
-  } __attribute((__packed__)) unaligned_uint32_t;
-
-  switch (nBytesToCopy)
+  if (nBytesPerSample == 1)
   {
-    case 1:
-      while((uint8_t *)dst < dst_end)
-      {
-        *(uint8_t *)dst++ = *src;
-        src += n_ff_used;
-      }
-      break;
-
-    case 2:
-      while((uint8_t *)dst < dst_end)
-      {
-        *(unaligned_uint16_t*)dst = *(unaligned_uint16_t*)src;
-        dst += 2;
-        src += 2 * n_ff_used;
-      }
-      break;
-
-    case 3:
-      while((uint8_t *)dst < dst_end)
-      {
-        //        memcpy(dst, src, 3);
-        //        dst = (uint8_t *)dst + 3;
-        //        src += 3 * n_ff_used;
-
-        // TODO: Is there a faster way to copy 3 bytes?
-        *(uint8_t *)dst++ = *src++;
-        *(uint8_t *)dst++ = *src++;
-        *(uint8_t *)dst++ = *src++;
-
-        src += 3 * (n_ff_used - 1);
-      }
-      break;
-
-    case 4:
-      while((uint8_t *)dst < dst_end)
-      {
-        *(unaligned_uint32_t*)dst = *(unaligned_uint32_t*)src;
-        dst += 4;
-        src += 4 * n_ff_used;
-      }
-      break;
+    while(dst16 < dst_end16)
+    {
+      *dst16++ = *src16++;
+      src16 += n_ff_used - 1;
+    }
+    return src16;
+  }
+  else if (nBytesPerSample == 2)
+  {
+    while(dst32 < dst_end32)
+    {
+      *dst32++ = *src32++;
+      src32 += n_ff_used - 1;
+    }
+    return src32;
+  }
+  else if (nBytesPerSample == 3)
+  {
+    while(dst16 < dst_end16)
+    {
+      *dst16++ = *src16++;
+      *dst16++ = *src16++;
+      *dst16++ = *src16++;
+      src16 += 3 * (n_ff_used - 1);
+    }
+    return src16;
+  }
+  else // nBytesPerSample == 4
+  {
+    while(dst32 < dst_end32)
+    {
+      *dst32++ = *src32++;
+      *dst32++ = *src32++;
+      src32 += 2 * (n_ff_used - 1);
+    }
+    return src32;
   }
-
-  return src;
 }
 
 static bool audiod_decode_type_I_pcm(uint8_t rhport, audiod_function_t* audio, uint16_t n_bytes_received)
@@ -826,9 +838,7 @@ uint16_t tud_audio_int_n_write(uint8_t func_id, uint8_t const* buffer, uint16_t
   TU_VERIFY(!usbd_edpt_busy(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int));
 
   // Check length
-  TU_VERIFY(len <= CFG_TUD_AUDIO_INT_EP_IN_SW_BUFFER_SIZE);
-
-  memcpy(_audiod_fct[func_id].ep_int_buf, buffer, len);
+  TU_VERIFY(tu_memcpy_s(_audiod_fct[func_id].ep_int_buf, CFG_TUD_AUDIO_INT_EP_IN_SW_BUFFER_SIZE,  buffer, len)==0);
 
   // Schedule transmit
   TU_VERIFY(usbd_edpt_xfer(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int, _audiod_fct[func_id].ep_int_buf, len));
@@ -838,7 +848,6 @@ uint16_t tud_audio_int_n_write(uint8_t func_id, uint8_t const* buffer, uint16_t
 
 #endif
 
-
 // This function is called once a transmit of an audio packet was successfully completed. Here, we encode samples and place it in IN EP's buffer for next transmission.
 // If you prefer your own (more efficient) implementation suiting your purpose set CFG_TUD_AUDIO_ENABLE_ENCODING = 0 and use tud_audio_n_write.
 
@@ -903,9 +912,12 @@ static bool audiod_tx_done_cb(uint8_t rhport, audiod_function_t * audio)
 
 #else
   // No support FIFOs, if no linear buffer required schedule transmit, else put data into linear buffer and schedule
-
+#if CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+  // packet_sz_tx is based on total packet size, here we want size for each support buffer.
+  n_bytes_tx = audiod_tx_packet_size(audio->packet_sz_tx, tu_fifo_count(&audio->ep_in_ff), audio->ep_in_ff.depth, audio->ep_in_sz);
+#else
   n_bytes_tx = tu_min16(tu_fifo_count(&audio->ep_in_ff), audio->ep_in_sz);      // Limit up to max packet size, more can not be done for ISO
-
+#endif
 #if USE_LINEAR_BUFFER_TX
   tu_fifo_read_n(&audio->ep_in_ff, audio->lin_buf_in, n_bytes_tx);
   TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_in, audio->lin_buf_in, n_bytes_tx));
@@ -943,64 +955,55 @@ range [-1, +1)
  * */
 
 // Helper function
-static inline uint8_t * audiod_interleaved_copy_bytes_fast_encode(uint16_t const nBytesToCopy, uint8_t * src, uint8_t * src_end, uint8_t * dst, uint8_t const n_ff_used)
+static inline void * audiod_interleaved_copy_bytes_fast_encode(uint16_t const nBytesPerSample, void * src, const void * src_end, void * dst, uint8_t const n_ff_used)
 {
-  // Optimize for fast half word copies
-  typedef struct{
-    uint16_t val;
-  } __attribute((__packed__)) unaligned_uint16_t;
-
-  // Optimize for fast word copies
-  typedef struct{
-    uint32_t val;
-  } __attribute((__packed__)) unaligned_uint32_t;
+  // Due to one FIFO contains 2 channels, data always aligned to (nBytesPerSample * 2)
+  uint16_t * dst16 = dst;
+  uint16_t * src16 = src;
+  const uint16_t * src_end16 = src_end;
+  uint32_t * dst32 = dst;
+  uint32_t * src32 = src;
+  const uint32_t * src_end32 = src_end;
 
-  switch (nBytesToCopy)
+  if (nBytesPerSample == 1)
   {
-    case 1:
-      while(src < src_end)
-      {
-        *dst = *src++;
-        dst += n_ff_used;
-      }
-      break;
-
-    case 2:
-      while(src < src_end)
-      {
-        *(unaligned_uint16_t*)dst = *(unaligned_uint16_t*)src;
-        src += 2;
-        dst += 2 * n_ff_used;
-      }
-      break;
-
-    case 3:
-      while(src < src_end)
-      {
-        //        memcpy(dst, src, 3);
-        //        src = (uint8_t *)src + 3;
-        //        dst += 3 * n_ff_used;
-
-        // TODO: Is there a faster way to copy 3 bytes?
-        *dst++ = *src++;
-        *dst++ = *src++;
-        *dst++ = *src++;
-
-        dst += 3 * (n_ff_used - 1);
-      }
-      break;
-
-    case 4:
-      while(src < src_end)
-      {
-        *(unaligned_uint32_t*)dst = *(unaligned_uint32_t*)src;
-        src += 4;
-        dst += 4 * n_ff_used;
-      }
-      break;
+    while(src16 < src_end16)
+    {
+      *dst16++ = *src16++;
+      dst16 += n_ff_used - 1;
+    }
+    return dst16;
+  }
+  else if (nBytesPerSample == 2)
+  {
+    while(src32 < src_end32)
+    {
+      *dst32++ = *src32++;
+      dst32 += n_ff_used - 1;
+    }
+    return dst32;
+  }
+  else if (nBytesPerSample == 3)
+  {
+    while(src16 < src_end16)
+    {
+      *dst16++ = *src16++;
+      *dst16++ = *src16++;
+      *dst16++ = *src16++;
+      dst16 += 3 * (n_ff_used - 1);
+    }
+    return dst16;
+  }
+  else // nBytesPerSample == 4
+  {
+    while(src32 < src_end32)
+    {
+      *dst32++ = *src32++;
+      *dst32++ = *src32++;
+      dst32 += 2 * (n_ff_used - 1);
+    }
+    return dst32;
   }
-
-  return dst;
 }
 
 static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_function_t* audio)
@@ -1013,8 +1016,6 @@ static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_function_t* audi
 
   // Determine amount of samples
   uint8_t const n_ff_used               = audio->n_ff_used_tx;
-  uint16_t const nBytesToCopy           = audio->n_channels_per_ff_tx * audio->n_bytes_per_sampe_tx;
-  uint16_t const capPerFF               = audio->ep_in_sz / n_ff_used;                                        // Sample capacity per FIFO in bytes
   uint16_t nBytesPerFFToSend            = tu_fifo_count(&audio->tx_supp_ff[0]);
   uint8_t cnt_ff;
 
@@ -1027,14 +1028,23 @@ static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_function_t* audi
     }
   }
 
-  // Check if there is enough
+#if CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+  const uint16_t norm_packet_sz_tx[3] = {audio->packet_sz_tx[0] / n_ff_used,
+                                         audio->packet_sz_tx[1] / n_ff_used,
+                                         audio->packet_sz_tx[2] / n_ff_used};
+  // packet_sz_tx is based on total packet size, here we want size for each support buffer.
+  nBytesPerFFToSend = audiod_tx_packet_size(norm_packet_sz_tx, nBytesPerFFToSend, audio->tx_supp_ff[0].depth, audio->ep_in_sz / n_ff_used);
+  // Check if there is enough data
+  if (nBytesPerFFToSend == 0)    return 0;
+#else
+  // Check if there is enough data
   if (nBytesPerFFToSend == 0)    return 0;
-
   // Limit to maximum sample number - THIS IS A POSSIBLE ERROR SOURCE IF TOO MANY SAMPLE WOULD NEED TO BE SENT BUT CAN NOT!
-  nBytesPerFFToSend = tu_min16(nBytesPerFFToSend, capPerFF);
-
+  nBytesPerFFToSend = tu_min16(nBytesPerFFToSend, audio->ep_in_sz / n_ff_used);
   // Round to full number of samples (flooring)
-  nBytesPerFFToSend = (nBytesPerFFToSend / nBytesToCopy) * nBytesToCopy;
+  uint16_t const nSlotSize = audio->n_channels_per_ff_tx * audio->n_bytes_per_sampe_tx;
+  nBytesPerFFToSend = (nBytesPerFFToSend / nSlotSize) * nSlotSize;
+#endif
 
   // Encode
   uint8_t * dst;
@@ -1339,7 +1349,7 @@ void audiod_init(void)
 #endif // CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
 
     // Set encoding parameters for Type_I formats
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
     switch (i)
     {
 #if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
@@ -1518,6 +1528,117 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
 #endif
       }
 
+#if USE_ISO_EP_ALLOCATION
+      {
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+        uint8_t  ep_in = 0;
+        uint16_t ep_in_size = 0;
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+        uint8_t  ep_out = 0;
+        uint16_t ep_out_size = 0;
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+        uint8_t ep_fb = 0;
+  #endif
+        uint8_t const *p_desc = _audiod_fct[i].p_desc;
+        uint8_t const *p_desc_end = p_desc + _audiod_fct[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
+        while (p_desc < p_desc_end)
+        {
+          if (tu_desc_type(p_desc) == TUSB_DESC_ENDPOINT)
+          {
+            tusb_desc_endpoint_t const *desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+            if (desc_ep->bmAttributes.xfer == TUSB_XFER_ISOCHRONOUS)
+            {
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+              // Explicit feedback EP
+              if (desc_ep->bmAttributes.usage == 1)
+              {
+                ep_fb = desc_ep->bEndpointAddress;
+              }
+  #endif
+              // Data EP
+              if (desc_ep->bmAttributes.usage == 0)
+              {
+                if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN)
+                {
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+                  ep_in = desc_ep->bEndpointAddress;
+                  ep_in_size = TU_MAX(tu_edpt_packet_size(desc_ep), ep_in_size);
+  #endif
+                } else
+                {
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+                  ep_out = desc_ep->bEndpointAddress;
+                  ep_out_size = TU_MAX(tu_edpt_packet_size(desc_ep), ep_out_size);
+  #endif
+                }
+              }
+
+            }
+          }
+
+          p_desc = tu_desc_next(p_desc);
+        }
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+        if (ep_in)
+        {
+          usbd_edpt_iso_alloc(rhport, ep_in, ep_in_size);
+        }
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+        if (ep_out)
+        {
+          usbd_edpt_iso_alloc(rhport, ep_out, ep_out_size);
+        }
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+        if (ep_fb)
+        {
+          usbd_edpt_iso_alloc(rhport, ep_fb, 4);
+        }
+  #endif
+      }
+#endif // USE_ISO_EP_ALLOCATION
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+      {
+        uint8_t const *p_desc = _audiod_fct[i].p_desc;
+        uint8_t const *p_desc_end = 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_ENDPOINT)
+          {
+            tusb_desc_endpoint_t const *desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+            if (desc_ep->bmAttributes.xfer == TUSB_XFER_ISOCHRONOUS)
+            {
+              if (desc_ep->bmAttributes.usage == 0)
+              {
+                if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN)
+                {
+                  _audiod_fct[i].interval_tx = desc_ep->bInterval;
+                }
+              }
+            }
+          } else
+          if (tu_desc_type(p_desc) == TUSB_DESC_CS_INTERFACE && tu_desc_subtype(p_desc) == AUDIO_CS_AC_INTERFACE_OUTPUT_TERMINAL)
+          {
+            if(tu_unaligned_read16(p_desc + 4) == AUDIO_TERM_TYPE_USB_STREAMING)
+            {
+               _audiod_fct[i].bclock_id_tx = p_desc[8];
+            }
+          }
+          p_desc = tu_desc_next(p_desc);
+        }
+      }
+#endif // CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+
       break;
     }
   }
@@ -1583,41 +1704,50 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
   if (audio->ep_in_as_intf_num == itf)
   {
     audio->ep_in_as_intf_num = 0;
+  #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_in);
+  #endif
 
     // Clear FIFOs, since data is no longer valid
-#if !CFG_TUD_AUDIO_ENABLE_ENCODING
+  #if !CFG_TUD_AUDIO_ENABLE_ENCODING
     tu_fifo_clear(&audio->ep_in_ff);
-#else
+  #else
     for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
     {
       tu_fifo_clear(&audio->tx_supp_ff[cnt]);
     }
-#endif
+  #endif
 
     // Invoke callback - can be used to stop data sampling
     if (tud_audio_set_itf_close_EP_cb) TU_VERIFY(tud_audio_set_itf_close_EP_cb(rhport, p_request));
 
     audio->ep_in = 0;                           // Necessary?
 
+  #if CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+    audio->packet_sz_tx[0] = 0;
+    audio->packet_sz_tx[1] = 0;
+    audio->packet_sz_tx[2] = 0;
+  #endif
   }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
   if (audio->ep_out_as_intf_num == itf)
   {
     audio->ep_out_as_intf_num = 0;
+  #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_out);
+  #endif
 
     // Clear FIFOs, since data is no longer valid
-#if !CFG_TUD_AUDIO_ENABLE_DECODING
+  #if !CFG_TUD_AUDIO_ENABLE_DECODING
     tu_fifo_clear(&audio->ep_out_ff);
-#else
+  #else
     for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
     {
       tu_fifo_clear(&audio->rx_supp_ff[cnt]);
     }
-#endif
+  #endif
 
     // Invoke callback - can be used to stop data sampling
     if (tud_audio_set_itf_close_EP_cb) TU_VERIFY(tud_audio_set_itf_close_EP_cb(rhport, p_request));
@@ -1625,13 +1755,15 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
     audio->ep_out = 0;                          // Necessary?
 
     // Close corresponding feedback EP
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+    #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_fb);
+    #endif
     audio->ep_fb = 0;
     tu_memclr(&audio->feedback, sizeof(audio->feedback));
-#endif
+  #endif
   }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
   // Save current alternative interface setting
   audio->alt_setting[idxItf] = alt;
@@ -1646,7 +1778,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
     // Find correct interface
     if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const * )p_desc)->bInterfaceNumber == itf && ((tusb_desc_interface_t const * )p_desc)->bAlternateSetting == alt)
     {
-#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+#if (CFG_TUD_AUDIO_ENABLE_EP_IN && (CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL || CFG_TUD_AUDIO_ENABLE_ENCODING)) || (CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING)
       uint8_t const * p_desc_parse_for_params = p_desc;
 #endif
       // From this point forward follow the EP descriptors associated to the current alternate setting interface - Open EPs if necessary
@@ -1656,8 +1788,11 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
         if (tu_desc_type(p_desc) == TUSB_DESC_ENDPOINT)
         {
           tusb_desc_endpoint_t const* desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+#if USE_ISO_EP_ALLOCATION
+          TU_ASSERT(usbd_edpt_iso_activate(rhport, desc_ep));
+#else
           TU_ASSERT(usbd_edpt_open(rhport, desc_ep));
-
+#endif
           uint8_t const ep_addr = desc_ep->bEndpointAddress;
 
           //TODO: We need to set EP non busy since this is not taken care of right now in ep_close() - THIS IS A WORKAROUND!
@@ -1672,21 +1807,21 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             audio->ep_in_sz = tu_edpt_packet_size(desc_ep);
 
             // If software encoding is enabled, parse for the corresponding parameters - doing this here means only AS interfaces with EPs get scanned for parameters
-#if CFG_TUD_AUDIO_ENABLE_ENCODING
+  #if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
             audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
 
             // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
-            const uint16_t active_fifo_depth = (uint16_t) ((audio->tx_supp_ff_sz_max / audio->n_bytes_per_sampe_tx) * audio->n_bytes_per_sampe_tx);
+    #if CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+            const uint16_t active_fifo_depth = (uint16_t) ((audio->tx_supp_ff_sz_max / (audio->n_channels_per_ff_tx * audio->n_bytes_per_sampe_tx))
+               * (audio->n_channels_per_ff_tx * audio->n_bytes_per_sampe_tx));
             for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
             {
               tu_fifo_config(&audio->tx_supp_ff[cnt], audio->tx_supp_ff[cnt].buffer, active_fifo_depth, 1, true);
             }
             audio->n_ff_used_tx = audio->n_channels_tx / audio->n_channels_per_ff_tx;
             TU_ASSERT( audio->n_ff_used_tx <= audio->n_tx_supp_ff );
-#endif
-
-#endif
+    #endif
+  #endif
 
             // Schedule first transmit if alternate interface is not zero i.e. streaming is disabled - in case no sample data is available a ZLP is loaded
             // It is necessary to trigger this here since the refill is done with an RX FIFO empty interrupt which can only trigger if something was in there
@@ -1703,11 +1838,11 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             audio->ep_out_as_intf_num = itf;
             audio->ep_out_sz = tu_edpt_packet_size(desc_ep);
 
-#if CFG_TUD_AUDIO_ENABLE_DECODING
+  #if CFG_TUD_AUDIO_ENABLE_DECODING
             audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
 
             // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+    #if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
             const uint16_t active_fifo_depth = (audio->rx_supp_ff_sz_max / audio->n_bytes_per_sampe_rx) * audio->n_bytes_per_sampe_rx;
             for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
             {
@@ -1715,18 +1850,18 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             }
             audio->n_ff_used_rx = audio->n_channels_rx / audio->n_channels_per_ff_rx;
             TU_ASSERT( audio->n_ff_used_rx <= audio->n_rx_supp_ff );
-#endif
-#endif
+    #endif
+  #endif
 
             // Prepare for incoming data
-#if USE_LINEAR_BUFFER_RX
+  #if USE_LINEAR_BUFFER_RX
             TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_out, audio->lin_buf_out, audio->ep_out_sz), false);
-#else
+  #else
             TU_VERIFY(usbd_edpt_xfer_fifo(rhport, audio->ep_out, &audio->ep_out_ff, audio->ep_out_sz), false);
-#endif
+  #endif
           }
 
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
           if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN && desc_ep->bmAttributes.usage == 1)   // Check if usage is explicit data feedback
           {
             audio->ep_fb = ep_addr;
@@ -1735,7 +1870,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             // Enable SOF interrupt if callback is implemented
             if (tud_audio_feedback_interval_isr) usbd_sof_enable(rhport, true);
           }
-#endif
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
           foundEPs += 1;
@@ -1786,7 +1921,7 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
           default: break;
         }
       }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 
       // We are done - abort loop
       break;
@@ -1810,6 +1945,10 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
   if (disable) usbd_sof_enable(rhport, false);
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+  audiod_calc_tx_packet_sz(audio);
+#endif
+
   tud_control_status(rhport, p_request);
 
   return true;
@@ -2084,7 +2223,7 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
     {
       if (tud_audio_fb_done_cb) tud_audio_fb_done_cb(func_id);
 
-      // Schedule a transmit with the new value if EP is not busy 
+      // Schedule a transmit with the new value if EP is not busy
       if (!usbd_edpt_busy(rhport, audio->ep_fb))
       {
         // Schedule next transmission - value is changed bytud_audio_n_fb_set() in the meantime or the old value gets sent
@@ -2250,7 +2389,20 @@ bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_req
   if (len > _audiod_fct[func_id].ctrl_buf_sz) len = _audiod_fct[func_id].ctrl_buf_sz;
 
   // Copy into buffer
-  memcpy((void *)_audiod_fct[func_id].ctrl_buf, data, (size_t)len);
+  TU_VERIFY(0 == tu_memcpy_s(_audiod_fct[func_id].ctrl_buf, _audiod_fct[func_id].ctrl_buf_sz, data, (size_t)len));
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+  // Find data for sampling_frequency_control
+  if (p_request->bmRequestType_bit.type == TUSB_REQ_TYPE_CLASS && p_request->bmRequestType_bit.recipient == TUSB_REQ_RCPT_INTERFACE)
+  {
+    uint8_t entityID = TU_U16_HIGH(p_request->wIndex);
+    uint8_t ctrlSel = TU_U16_HIGH(p_request->wValue);
+    if (_audiod_fct[func_id].bclock_id_tx == entityID && ctrlSel == AUDIO_CS_CTRL_SAM_FREQ && p_request->bRequest == AUDIO_CS_REQ_CUR)
+    {
+      _audiod_fct[func_id].sample_rate_tx = tu_unaligned_read32(_audiod_fct[func_id].ctrl_buf);
+    }
+  }
+#endif
 
   // Schedule transmit
   return tud_control_xfer(rhport, p_request, (void*)_audiod_fct[func_id].ctrl_buf, len);
@@ -2391,7 +2543,7 @@ static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *func_id)
   return false;
 }
 
-#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+#if (CFG_TUD_AUDIO_ENABLE_EP_IN && (CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL || CFG_TUD_AUDIO_ENABLE_ENCODING)) || (CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING)
 // p_desc points to the AS interface of alternate setting zero
 // itf is the interface number of the corresponding interface - we check if the interface belongs to EP in or EP out to see if it is a TX or RX parameter
 // Currently, only AS interfaces with an EP (in or out) are supposed to be parsed for!
@@ -2429,7 +2581,7 @@ static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const *
       }
 #endif
 
-#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
       if (as_itf == audio->ep_out_as_intf_num)
       {
         audio->n_channels_rx = ((audio_desc_cs_as_interface_t const * )p_desc)->bNrChannels;
@@ -2442,7 +2594,7 @@ static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const *
     }
 
     // Look for a Type I Format Type Descriptor(2.3.1.6 - Audio Formats)
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING || CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING || CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL || CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
     if (tu_desc_type(p_desc) == TUSB_DESC_CS_INTERFACE && tu_desc_subtype(p_desc) == AUDIO_CS_AS_INTERFACE_FORMAT_TYPE && ((audio_desc_type_I_format_t const * )p_desc)->bFormatType == AUDIO_FORMAT_TYPE_I)
     {
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
@@ -2462,7 +2614,7 @@ static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const *
       }
 #endif
 
-#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
       if (as_itf == audio->ep_out_as_intf_num)
       {
         audio->n_bytes_per_sampe_rx = ((audio_desc_type_I_format_t const * )p_desc)->bSubslotSize;
@@ -2478,6 +2630,96 @@ static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const *
 }
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
+
+static bool audiod_calc_tx_packet_sz(audiod_function_t* audio)
+{
+  TU_VERIFY(audio->format_type_tx == AUDIO_FORMAT_TYPE_I);
+  TU_VERIFY(audio->n_channels_tx);
+  TU_VERIFY(audio->n_bytes_per_sampe_tx);
+  TU_VERIFY(audio->interval_tx);
+  TU_VERIFY(audio->sample_rate_tx);
+
+  const uint8_t interval = (tud_speed_get() == TUSB_SPEED_FULL) ? audio->interval_tx : 1 << (audio->interval_tx - 1);
+
+  const uint16_t sample_normimal = (uint16_t)(audio->sample_rate_tx * interval / ((tud_speed_get() == TUSB_SPEED_FULL) ? 1000 : 8000));
+  const uint16_t sample_reminder = (uint16_t)(audio->sample_rate_tx * interval % ((tud_speed_get() == TUSB_SPEED_FULL) ? 1000 : 8000));
+
+  const uint16_t packet_sz_tx_min = (uint16_t)((sample_normimal - 1) * audio->n_channels_tx * audio->n_bytes_per_sampe_tx);
+  const uint16_t packet_sz_tx_norm = (uint16_t)(sample_normimal * audio->n_channels_tx * audio->n_bytes_per_sampe_tx);
+  const uint16_t packet_sz_tx_max = (uint16_t)((sample_normimal + 1) * audio->n_channels_tx * audio->n_bytes_per_sampe_tx);
+
+  // Endpoint size must larger than packet size
+  TU_ASSERT(packet_sz_tx_max <= audio->ep_in_sz);
+
+  // Frmt20.pdf 2.3.1.1 USB Packets
+  if (sample_reminder)
+  {
+    // All virtual frame packets must either contain INT(nav) audio slots (small VFP) or INT(nav)+1 (large VFP) audio slots
+    audio->packet_sz_tx[0] = packet_sz_tx_norm;
+    audio->packet_sz_tx[1] = packet_sz_tx_norm;
+    audio->packet_sz_tx[2] = packet_sz_tx_max;
+  } else
+  {
+    // In the case where nav = INT(nav), ni may vary between INT(nav)-1 (small VFP), INT(nav)
+    // (medium VFP) and INT(nav)+1 (large VFP).
+    audio->packet_sz_tx[0] = packet_sz_tx_min;
+    audio->packet_sz_tx[1] = packet_sz_tx_norm;
+    audio->packet_sz_tx[2] = packet_sz_tx_max;
+  }
+
+  return true;
+}
+
+static uint16_t audiod_tx_packet_size(const uint16_t* norminal_size, uint16_t data_count, uint16_t fifo_depth, uint16_t max_depth)
+{
+  // Flow control need a FIFO size of at least 4*Navg
+  if(norminal_size[1] && norminal_size[1] <= fifo_depth * 4)
+  {
+    // Use blackout to prioritize normal size packet
+    static int ctrl_blackout = 0;
+    uint16_t packet_size;
+    uint16_t slot_size = norminal_size[2] - norminal_size[1];
+    if (data_count < norminal_size[0])
+    {
+        // If you get here frequently, then your I2S clock deviation is too big !
+        packet_size = 0;
+    } else
+    if (data_count < fifo_depth / 2 - slot_size && !ctrl_blackout)
+    {
+      packet_size = norminal_size[0];
+      ctrl_blackout = 10;
+    } else
+    if (data_count > fifo_depth / 2 + slot_size && !ctrl_blackout)
+    {
+      packet_size = norminal_size[2];
+      if(norminal_size[0] == norminal_size[1])
+      {
+        // nav > INT(nav), eg. 44.1k, 88.2k
+        ctrl_blackout = 0;
+      } else
+      {
+        // nav = INT(nav), eg. 48k, 96k
+        ctrl_blackout = 10;
+      }
+    } else
+    {
+      packet_size = norminal_size[1];
+      if (ctrl_blackout)
+      {
+        ctrl_blackout--;
+      }
+    }
+    // Normally this cap is not necessary
+    return tu_min16(packet_size, max_depth);
+  } else
+  {
+    return tu_min16(data_count, max_depth);
+  }
+}
+
+#endif
+
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 
 bool tud_audio_n_fb_set(uint8_t func_id, uint32_t feedback)