diff --git a/src/portable/nuvoton/nuc121/dcd_nuc121.c b/src/portable/nuvoton/nuc121/dcd_nuc121.c
index 4e0a583e..25d723d9 100644
--- a/src/portable/nuvoton/nuc121/dcd_nuc121.c
+++ b/src/portable/nuvoton/nuc121/dcd_nuc121.c
@@ -148,6 +148,37 @@ static void dcd_in_xfer(struct xfer_ctl_t *xfer, USBD_EP_T *ep)
   ep->MXPLD = bytes_now;
 }
 
+/* called by dcd_init() as well as by the ISR during a USB bus reset */
+static void bus_reset(void)
+{
+  USBD->STBUFSEG = PERIPH_SETUP_BUF_BASE;
+
+  for (enum ep_enum ep_index = PERIPH_EP0; ep_index < PERIPH_MAX_EP; ep_index++)
+  {
+    USBD->EP[ep_index].CFG = 0;
+    USBD->EP[ep_index].CFGP = 0;
+  }
+
+  /* allocate the default EP0 endpoints */
+
+  USBD->EP[PERIPH_EP0].CFG = USBD_CFG_CSTALL_Msk | USBD_CFG_EPMODE_IN;
+  USBD->EP[PERIPH_EP0].BUFSEG = PERIPH_EP0_BUF_BASE;
+  xfer_table[PERIPH_EP0].max_packet_size = PERIPH_EP0_BUF_LEN;
+
+  USBD->EP[PERIPH_EP1].CFG = USBD_CFG_CSTALL_Msk | USBD_CFG_EPMODE_OUT;
+  USBD->EP[PERIPH_EP1].BUFSEG = PERIPH_EP1_BUF_BASE;
+  xfer_table[PERIPH_EP1].max_packet_size = PERIPH_EP1_BUF_LEN;
+
+  /* USB RAM beyond what we've allocated above is available to the user */
+  bufseg_addr = PERIPH_EP2_BUF_BASE;
+
+  /* Reset USB device address */
+  USBD->FADDR = 0;
+
+  /* reset EP0_IN flag */
+  active_ep0_xfer = false;
+}
+
 /* centralized location for USBD interrupt enable bit mask */
 static const uint32_t enabled_irqs = USBD_INTSTS_VBDETIF_Msk | USBD_INTSTS_BUSIF_Msk | USBD_INTSTS_SETUP_Msk | USBD_INTSTS_USBIF_Msk | USBD_INTSTS_SOFIF_Msk;
 
@@ -167,25 +198,7 @@ void dcd_init(uint8_t rhport)
 
   usb_detach();
 
-  USBD->STBUFSEG = PERIPH_SETUP_BUF_BASE;
-
-  for (enum ep_enum ep_index = PERIPH_EP0; ep_index < PERIPH_MAX_EP; ep_index++)
-  {
-    USBD->EP[ep_index].CFGP &= ~USBD_CFG_STATE_Msk;
-  }
-
-  /* allocate the default EP0 endpoints */
-
-  USBD->EP[PERIPH_EP0].CFG = USBD_CFG_CSTALL_Msk | USBD_CFG_EPMODE_IN;
-  USBD->EP[PERIPH_EP0].BUFSEG = PERIPH_EP0_BUF_BASE;
-  xfer_table[PERIPH_EP0].max_packet_size = PERIPH_EP0_BUF_LEN;
-
-  USBD->EP[PERIPH_EP1].CFG = USBD_CFG_CSTALL_Msk | USBD_CFG_EPMODE_OUT;
-  USBD->EP[PERIPH_EP1].BUFSEG = PERIPH_EP1_BUF_BASE;
-  xfer_table[PERIPH_EP1].max_packet_size = PERIPH_EP1_BUF_LEN;
-
-  /* USB RAM beyond what we've allocated above is available to the user */
-  bufseg_addr = PERIPH_EP2_BUF_BASE;
+  bus_reset();
 
   usb_attach();
 
@@ -329,15 +342,7 @@ void USBD_IRQHandler(void)
       /* USB bus reset */
       USBD->ATTR |= USBD_ATTR_USBEN_Msk | USBD_ATTR_PHYEN_Msk;
 
-      /* Reset all endpoints to DATA0 */
-      for(enum ep_enum ep_index = PERIPH_EP0; ep_index < PERIPH_MAX_EP; ep_index++)
-        USBD->EP[ep_index].CFG &= ~USBD_CFG_DSQSYNC_Msk;
-
-      /* Reset USB device address */
-      USBD->FADDR = 0;
-
-      /* reset EP0_IN flag */
-      active_ep0_xfer = false;
+      bus_reset();
 
       dcd_event_bus_signal(0, DCD_EVENT_BUS_RESET, true);
     }
diff --git a/src/portable/nxp/transdimension/dcd_transdimension.c b/src/portable/nxp/transdimension/dcd_transdimension.c
index 2ec7ae51..77e355ed 100644
--- a/src/portable/nxp/transdimension/dcd_transdimension.c
+++ b/src/portable/nxp/transdimension/dcd_transdimension.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -313,6 +313,10 @@ void dcd_init(uint8_t rhport)
   // TODO Force fullspeed on non-highspeed port
   // dcd_reg->PORTSC1 = PORTSC1_FORCE_FULL_SPEED;
 
+  #if defined(__CORTEX_M) && __CORTEX_M == 7 && __DCACHE_PRESENT == 1
+  SCB_CleanInvalidateDCache_by_Addr((uint32_t*) &_dcd_data, sizeof(dcd_data_t));
+  #endif
+
   dcd_reg->ENDPTLISTADDR = (uint32_t) _dcd_data.qhd; // Endpoint List Address has to be 2K alignment
   dcd_reg->USBSTS  = dcd_reg->USBSTS;
   dcd_reg->USBINTR = INTR_USB | INTR_ERROR | INTR_PORT_CHANGE | INTR_RESET | INTR_SUSPEND | INTR_SOF;
@@ -419,6 +423,10 @@ bool dcd_edpt_open(uint8_t rhport, tusb_desc_endpoint_t const * p_endpoint_desc)
   p_qhd->max_package_size        = p_endpoint_desc->wMaxPacketSize.size;
   p_qhd->qtd_overlay.next        = QTD_NEXT_INVALID;
 
+  #if defined(__CORTEX_M) && __CORTEX_M == 7 && __DCACHE_PRESENT == 1
+  SCB_CleanInvalidateDCache_by_Addr((uint32_t*) &_dcd_data, sizeof(dcd_data_t));
+  #endif
+
   // Enable EP Control
   DCD_REGS[rhport]->ENDPTCTRL[epnum] |= ((p_endpoint_desc->bmAttributes.xfer << 2) | ENDPTCTRL_ENABLE | ENDPTCTRL_TOGGLE_RESET) << (dir ? 16 : 0);
 
@@ -441,10 +449,19 @@ bool dcd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t t
   dcd_qhd_t * p_qhd = &_dcd_data.qhd[ep_idx];
   dcd_qtd_t * p_qtd = &_dcd_data.qtd[ep_idx];
 
+  // Force the CPU to flush the buffer. We increase the size by 32 because the call aligns the
+  // address to 32-byte boundaries.
+  #if defined(__CORTEX_M) && __CORTEX_M == 7 && __DCACHE_PRESENT == 1
+  SCB_CleanInvalidateDCache_by_Addr((uint32_t*) buffer, total_bytes + 31);
+  #endif
+
   //------------- Prepare qtd -------------//
   qtd_init(p_qtd, buffer, total_bytes);
   p_qtd->int_on_complete = true;
   p_qhd->qtd_overlay.next = (uint32_t) p_qtd; // link qtd to qhd
+  #if defined(__CORTEX_M) && __CORTEX_M == 7 && __DCACHE_PRESENT == 1
+  SCB_CleanInvalidateDCache_by_Addr((uint32_t*) &_dcd_data, sizeof(dcd_data_t));
+  #endif
 
   // start transfer
   DCD_REGS[rhport]->ENDPTPRIME = TU_BIT( ep_idx2bit(ep_idx) ) ;
@@ -484,6 +501,11 @@ void dcd_isr(uint8_t rhport)
     }
   }
 
+  // Make sure we read the latest version of _dcd_data.
+  #if defined(__CORTEX_M) && __CORTEX_M == 7 && __DCACHE_PRESENT == 1
+  SCB_CleanInvalidateDCache_by_Addr((uint32_t*) &_dcd_data, sizeof(dcd_data_t));
+  #endif
+
   // TODO disconnection does not generate interrupt !!!!!!
 //	if (int_status & INTR_PORT_CHANGE)
 //	{