diff --git a/port/chipidea/usb_dc_chipidea.c b/port/chipidea/usb_dc_chipidea.c
index c6b6c0fe..9616dcc2 100644
--- a/port/chipidea/usb_dc_chipidea.c
+++ b/port/chipidea/usb_dc_chipidea.c
@@ -525,10 +525,7 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
 {
     uint8_t ep_idx = USB_EP_GET_IDX(ep->bEndpointAddress);
 
-    /* Must not exceed max endpoint number */
-    if (ep_idx >= CONFIG_USBDEV_EP_NUM) {
-        return -1;
-    }
+    USB_ASSERT_MSG(ep_idx < CONFIG_USBDEV_EP_NUM, "Ep addr %02x overflow", ep->bEndpointAddress);
 
     chipidea_edpt_open(busid, ep->bEndpointAddress, USB_GET_ENDPOINT_TYPE(ep->bmAttributes), ep->wMaxPacketSize);
 
@@ -666,17 +663,10 @@ void USBD_IRQHandler(uint8_t busid)
 
     if (int_status & intr_usb) {
         uint32_t const edpt_complete = USB_OTG_DEV->ENDPTCOMPLETE;
-        USB_OTG_DEV->ENDPTCOMPLETE = edpt_complete;
         uint32_t edpt_setup_status = USB_OTG_DEV->ENDPTSETUPSTAT;
 
-        if (edpt_setup_status) {
-            /*------------- Set up Received -------------*/
-            USB_OTG_DEV->ENDPTSETUPSTAT = edpt_setup_status;
-            dcd_qhd_t *qhd0 = chipidea_qhd_get(busid, 0);
-            usbd_event_ep0_setup_complete_handler(busid, (uint8_t *)&qhd0->setup_request);
-        }
-
         if (edpt_complete) {
+            USB_OTG_DEV->ENDPTCOMPLETE = edpt_complete;
             for (uint8_t ep_idx = 0; ep_idx < (CONFIG_USBDEV_EP_NUM * 2); ep_idx++) {
                 if (edpt_complete & (1 << ep_idx2bit(ep_idx))) {
                     transfer_len = 0;
@@ -714,5 +704,12 @@ void USBD_IRQHandler(uint8_t busid)
                 }
             }
         }
+
+        if (edpt_setup_status) {
+            /*------------- Set up Received -------------*/
+            USB_OTG_DEV->ENDPTSETUPSTAT = edpt_setup_status;
+            dcd_qhd_t *qhd0 = chipidea_qhd_get(busid, 0);
+            usbd_event_ep0_setup_complete_handler(busid, (uint8_t *)&qhd0->setup_request);
+        }
     }
 }
\ No newline at end of file
diff --git a/port/dwc2/usb_dc_dwc2.c b/port/dwc2/usb_dc_dwc2.c
index d3b33a5d..88813991 100644
--- a/port/dwc2/usb_dc_dwc2.c
+++ b/port/dwc2/usb_dc_dwc2.c
@@ -711,10 +711,7 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
 {
     uint8_t ep_idx = USB_EP_GET_IDX(ep->bEndpointAddress);
 
-    if (ep_idx > (CONFIG_USBDEV_EP_NUM - 1)) {
-        USB_LOG_ERR("Ep addr %02x overflow\r\n", ep->bEndpointAddress);
-        return -1;
-    }
+    USB_ASSERT_MSG(ep_idx < CONFIG_USBDEV_EP_NUM, "Ep addr %02x overflow", ep->bEndpointAddress);
 
     if (USB_EP_DIR_IS_OUT(ep->bEndpointAddress)) {
         g_dwc2_udc[busid].out_ep[ep_idx].ep_mps = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
@@ -735,10 +732,8 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         } else {
             fifo_size = (USB_OTG_GLB->DIEPTXF[ep_idx - 1U] >> 16);
         }
-        if ((fifo_size * 4) < USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize)) {
-            USB_LOG_ERR("Ep addr %02x fifo overflow\r\n", ep->bEndpointAddress);
-            return -2;
-        }
+
+        USB_ASSERT_MSG((fifo_size * 4) >= USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize), "Ep addr %02x fifo overflow", ep->bEndpointAddress);
 
         g_dwc2_udc[busid].in_ep[ep_idx].ep_mps = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
         g_dwc2_udc[busid].in_ep[ep_idx].ep_type = USB_GET_ENDPOINT_TYPE(ep->bmAttributes);
@@ -880,7 +875,7 @@ int usbd_ep_start_write(uint8_t busid, const uint8_t ep, const uint8_t *data, ui
     }
 
     if (ep_idx && !(USB_OTG_INEP(ep_idx)->DIEPCTL & USB_OTG_DIEPCTL_MPSIZ)) {
-        return -3;
+        return -2;
     }
 
     g_dwc2_udc[busid].in_ep[ep_idx].xfer_buf = (uint8_t *)data;
@@ -948,7 +943,7 @@ int usbd_ep_start_read(uint8_t busid, const uint8_t ep, uint8_t *data, uint32_t
     }
 
     if (ep_idx && !(USB_OTG_OUTEP(ep_idx)->DOEPCTL & USB_OTG_DOEPCTL_MPSIZ)) {
-        return -3;
+        return -2;
     }
 
     g_dwc2_udc[busid].out_ep[ep_idx].xfer_buf = (uint8_t *)data;
diff --git a/port/fsdev/usb_dc_fsdev.c b/port/fsdev/usb_dc_fsdev.c
index f27e8c69..d046aa93 100644
--- a/port/fsdev/usb_dc_fsdev.c
+++ b/port/fsdev/usb_dc_fsdev.c
@@ -131,10 +131,7 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
 {
     uint8_t ep_idx = USB_EP_GET_IDX(ep->bEndpointAddress);
 
-    if (ep_idx > (CONFIG_USBDEV_EP_NUM - 1)) {
-        USB_LOG_ERR("Ep addr %02x overflow\r\n", ep->bEndpointAddress);
-        return -1;
-    }
+    USB_ASSERT_MSG(ep_idx < CONFIG_USBDEV_EP_NUM, "Ep addr %02x overflow", ep->bEndpointAddress);
 
     uint16_t wEpRegVal;
 
@@ -169,10 +166,9 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         g_fsdev_udc.out_ep[ep_idx].ep_type = USB_GET_ENDPOINT_TYPE(ep->bmAttributes);
         g_fsdev_udc.out_ep[ep_idx].ep_enable = true;
         if (g_fsdev_udc.out_ep[ep_idx].ep_mps > g_fsdev_udc.out_ep[ep_idx].ep_pma_buf_len) {
-            if (g_fsdev_udc.pma_offset + g_fsdev_udc.out_ep[ep_idx].ep_mps > CONFIG_USB_FSDEV_RAM_SIZE) {
-                USB_LOG_ERR("Ep pma %02x overflow\r\n", ep->bEndpointAddress);
-                return -1;
-            }
+            USB_ASSERT_MSG((g_fsdev_udc.pma_offset + g_fsdev_udc.out_ep[ep_idx].ep_mps) <= CONFIG_USB_FSDEV_RAM_SIZE,
+                           "Ep pma %02x overflow", ep->bEndpointAddress);
+
             g_fsdev_udc.out_ep[ep_idx].ep_pma_buf_len = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
             g_fsdev_udc.out_ep[ep_idx].ep_pma_addr = g_fsdev_udc.pma_offset;
             /*Set the endpoint Receive buffer address */
@@ -187,10 +183,9 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         g_fsdev_udc.in_ep[ep_idx].ep_type = USB_GET_ENDPOINT_TYPE(ep->bmAttributes);
         g_fsdev_udc.in_ep[ep_idx].ep_enable = true;
         if (g_fsdev_udc.in_ep[ep_idx].ep_mps > g_fsdev_udc.in_ep[ep_idx].ep_pma_buf_len) {
-            if (g_fsdev_udc.pma_offset + g_fsdev_udc.in_ep[ep_idx].ep_mps > CONFIG_USB_FSDEV_RAM_SIZE) {
-                USB_LOG_ERR("Ep pma %02x overflow\r\n", ep->bEndpointAddress);
-                return -1;
-            }
+            USB_ASSERT_MSG((g_fsdev_udc.pma_offset + g_fsdev_udc.in_ep[ep_idx].ep_mps) <= CONFIG_USB_FSDEV_RAM_SIZE,
+                           "Ep pma %02x overflow", ep->bEndpointAddress);
+
             g_fsdev_udc.in_ep[ep_idx].ep_pma_buf_len = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
             g_fsdev_udc.in_ep[ep_idx].ep_pma_addr = g_fsdev_udc.pma_offset;
             /*Set the endpoint Transmit buffer address */
diff --git a/port/kinetis/usb_dc_kinetis.c b/port/kinetis/usb_dc_kinetis.c
index dd4e4f98..eb819576 100644
--- a/port/kinetis/usb_dc_kinetis.c
+++ b/port/kinetis/usb_dc_kinetis.c
@@ -156,9 +156,7 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
     uint8_t regval;
 
     /* Must not exceed max endpoint number */
-    if (ep_idx >= CONFIG_USBDEV_EP_NUM) {
-        return -1;
-    }
+    USB_ASSERT_MSG(ep_idx < CONFIG_USBDEV_EP_NUM, "Ep addr %02x overflow", ep->bEndpointAddress);
 
     if (USB_EP_DIR_IS_OUT(ep->bEndpointAddress)) {
         g_kinetis_udc[busid].out_ep[ep_idx].ep_mps = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
diff --git a/port/musb/usb_dc_musb.c b/port/musb/usb_dc_musb.c
index 753e45bf..0d759b58 100644
--- a/port/musb/usb_dc_musb.c
+++ b/port/musb/usb_dc_musb.c
@@ -331,10 +331,7 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         return 0;
     }
 
-    if (ep_idx > (CONFIG_USBDEV_EP_NUM - 1)) {
-        USB_LOG_ERR("Ep addr %02x overflow\r\n", ep->bEndpointAddress);
-        return -1;
-    }
+    USB_ASSERT_MSG(ep_idx < CONFIG_USBDEV_EP_NUM, "Ep addr %02x overflow", ep->bEndpointAddress);
 
     old_ep_idx = musb_get_active_ep();
     musb_set_active_ep(ep_idx);
@@ -344,10 +341,8 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         g_musb_udc.out_ep[ep_idx].ep_type = USB_GET_ENDPOINT_TYPE(ep->bmAttributes);
         g_musb_udc.out_ep[ep_idx].ep_enable = true;
 
-        if ((8 << HWREGB(USB_BASE + MUSB_RXFIFOSZ_OFFSET)) < g_musb_udc.out_ep[ep_idx].ep_mps) {
-            USB_LOG_ERR("Ep %02x fifo is overflow\r\n", ep->bEndpointAddress);
-            return -2;
-        }
+        USB_ASSERT_MSG((8 << HWREGB(USB_BASE + MUSB_RXFIFOSZ_OFFSET)) >= g_musb_udc.out_ep[ep_idx].ep_mps,
+                       "Ep %02x fifo is overflow", ep->bEndpointAddress);
 
         HWREGH(USB_BASE + MUSB_IND_RXMAP_OFFSET) = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);
 
@@ -395,10 +390,8 @@ int usbd_ep_open(uint8_t busid, const struct usb_endpoint_descriptor *ep)
         g_musb_udc.in_ep[ep_idx].ep_type = USB_GET_ENDPOINT_TYPE(ep->bmAttributes);
         g_musb_udc.in_ep[ep_idx].ep_enable = true;
 
-        if ((8 << HWREGB(USB_BASE + MUSB_TXFIFOSZ_OFFSET)) < g_musb_udc.in_ep[ep_idx].ep_mps) {
-            USB_LOG_ERR("Ep %02x fifo is overflow\r\n", ep->bEndpointAddress);
-            return -2;
-        }
+        USB_ASSERT_MSG((8 << HWREGB(USB_BASE + MUSB_TXFIFOSZ_OFFSET)) >= g_musb_udc.in_ep[ep_idx].ep_mps,
+                       "Ep %02x fifo is overflow", ep->bEndpointAddress);
 
         HWREGH(USB_BASE + MUSB_IND_TXMAP_OFFSET) = USB_GET_MAXPACKETSIZE(ep->wMaxPacketSize);