diff --git a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
index c1d550ea8..1d3d8cd96 100644
--- a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
+++ b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
@@ -375,7 +375,7 @@ static void dcd_ep_ctr_rx_handler(uint32_t ep_id) {
   } else {
     ep_reg &= USB_EPRX_STAT | USB_EPREG_MASK; // reversed all toggle except RX Status
 
-    bool const is_iso = (ep_reg & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS;
+    bool const is_iso = ep_is_iso(ep_reg);
     xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
 
     uint8_t buf_id;
@@ -748,9 +748,8 @@ static void dcd_transmit_packet(xfer_ctl_t *xfer, uint16_t ep_ix) {
   dcd_int_enable(0);
 }
 
-static bool edpt_xfer(uint8_t rhport, uint8_t ep_addr)
-{
-  (void)rhport;
+static bool edpt_xfer(uint8_t rhport, uint8_t ep_addr) {
+  (void) rhport;
 
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
   uint8_t const ep_idx = xfer->ep_idx;
@@ -762,7 +761,7 @@ static bool edpt_xfer(uint8_t rhport, uint8_t ep_addr)
     uint32_t cnt = (uint32_t) tu_min16(xfer->total_len, xfer->max_packet_size);
     uint16_t ep_reg = pcd_get_endpoint(USB, ep_idx);
 
-    if ((ep_reg & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS) {
+    if (ep_is_iso(ep_reg)) {
       btable_set_rx_bufsize(ep_idx, 0, cnt);
       btable_set_rx_bufsize(ep_idx, 1, cnt);
     } else {
@@ -775,10 +774,8 @@ static bool edpt_xfer(uint8_t rhport, uint8_t ep_addr)
   return true;
 }
 
-bool dcd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t *buffer, uint16_t total_bytes)
-{
+bool dcd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t *buffer, uint16_t total_bytes) {
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
-
   xfer->buffer = buffer;
   xfer->ff = NULL;
   xfer->total_len = total_bytes;
@@ -787,8 +784,7 @@ bool dcd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t *buffer, uint16_t to
   return edpt_xfer(rhport, ep_addr);
 }
 
-bool dcd_edpt_xfer_fifo(uint8_t rhport, uint8_t ep_addr, tu_fifo_t *ff, uint16_t total_bytes)
-{
+bool dcd_edpt_xfer_fifo(uint8_t rhport, uint8_t ep_addr, tu_fifo_t *ff, uint16_t total_bytes) {
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
   xfer->buffer = NULL;
   xfer->ff = ff;
@@ -798,19 +794,19 @@ bool dcd_edpt_xfer_fifo(uint8_t rhport, uint8_t ep_addr, tu_fifo_t *ff, uint16_t
   return edpt_xfer(rhport, ep_addr);
 }
 
-void dcd_edpt_stall(uint8_t rhport, uint8_t ep_addr)
-{
+void dcd_edpt_stall(uint8_t rhport, uint8_t ep_addr) {
   (void)rhport;
 
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
   uint8_t const ep_idx = xfer->ep_idx;
   uint8_t const dir = tu_edpt_dir(ep_addr);
 
-  if (dir == TUSB_DIR_IN) {
-    pcd_set_ep_tx_status(USB, ep_idx, USB_EP_TX_STALL);
-  } else {
-    pcd_set_ep_rx_status(USB, ep_idx, USB_EP_RX_STALL);
-  }
+  uint32_t ep_reg = pcd_get_endpoint(USB, ep_idx);
+  ep_reg |= USB_EP_CTR_RX | USB_EP_CTR_TX; // reserve CTR bits
+  ep_reg &= USB_EPREG_MASK | EP_STAT_MASK(dir);
+  ep_reg = ep_add_status(ep_reg, dir, EP_STAT_STALL);
+
+  pcd_set_endpoint(USB, ep_idx, ep_reg);
 }
 
 void dcd_edpt_clear_stall(uint8_t rhport, uint8_t ep_addr) {
@@ -819,23 +815,16 @@ void dcd_edpt_clear_stall(uint8_t rhport, uint8_t ep_addr) {
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_addr);
   uint8_t const ep_idx = xfer->ep_idx;
   uint8_t const dir = tu_edpt_dir(ep_addr);
+  uint32_t ep_reg = pcd_get_endpoint(USB, ep_idx);
+  ep_reg |= USB_EP_CTR_RX | USB_EP_CTR_TX; // reserve CTR bits
+  ep_reg &= USB_EPREG_MASK | EP_STAT_MASK(dir) | EP_DTOG_MASK(dir);
 
-//  uint32_t ep_reg = pcd_get_endpoint(USB, ep_idx);
-
-  if (dir == TUSB_DIR_IN) { // IN
-    if (pcd_get_eptype(USB, ep_idx) != USB_EP_ISOCHRONOUS) {
-      pcd_set_ep_tx_status(USB, ep_idx, USB_EP_TX_NAK);
-    }
-
-    /* Reset to DATA0 if clearing stall condition. */
-    pcd_clear_tx_dtog(USB, ep_idx);
-  } else { // OUT
-    if (pcd_get_eptype(USB, ep_idx) != USB_EP_ISOCHRONOUS) {
-      pcd_set_ep_rx_status(USB, ep_idx, USB_EP_RX_NAK);
-    }
-    /* Reset to DATA0 if clearing stall condition. */
-    pcd_clear_rx_dtog(USB, ep_idx);
+  if (!ep_is_iso(ep_reg)) {
+    ep_reg = ep_add_status(ep_reg, dir, EP_STAT_NAK);
   }
+  ep_reg = ep_add_dtog(ep_reg, dir, 0); // Reset to DATA0
+
+  pcd_set_endpoint(USB, ep_idx, ep_reg);
 }
 
 #ifdef FSDEV_BUS_32BIT
diff --git a/src/portable/st/stm32_fsdev/fsdev_common.h b/src/portable/st/stm32_fsdev/fsdev_common.h
index 676596c73..3b14c0334 100644
--- a/src/portable/st/stm32_fsdev/fsdev_common.h
+++ b/src/portable/st/stm32_fsdev/fsdev_common.h
@@ -159,6 +159,9 @@ typedef enum {
   EP_STAT_VALID = 3
 }ep_stat_t;
 
+#define EP_STAT_MASK(_dir)  (3u << (USB_EPTX_STAT_Pos + ((_dir) == TUSB_DIR_IN ? 0 : 8)))
+#define EP_DTOG_MASK(_dir)  (1u << (USB_EP_DTOG_TX_Pos + ((_dir) == TUSB_DIR_IN ? 0 : 8)))
+
 //--------------------------------------------------------------------+
 // BTable
 //--------------------------------------------------------------------+
@@ -274,26 +277,6 @@ TU_ATTR_ALWAYS_INLINE static inline void pcd_set_eptype(USB_TypeDef * USBx, uint
   pcd_set_endpoint(USBx, bEpIdx, regVal);
 }
 
-TU_ATTR_ALWAYS_INLINE static inline uint32_t pcd_get_eptype(USB_TypeDef * USBx, uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  regVal &= USB_EP_T_FIELD;
-  return regVal;
-}
-
-/**
-  * @brief  Clears bit CTR_RX / CTR_TX in the endpoint register.
-  * @param  USBx USB peripheral instance register address.
-  * @param  bEpIdx Endpoint Number.
-  * @retval None
-  */
-TU_ATTR_ALWAYS_INLINE static inline void pcd_clear_rx_ep_ctr(USB_TypeDef * USBx, uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  regVal &= USB_EPREG_MASK;
-  regVal &= ~USB_EP_CTR_RX;
-  regVal |= USB_EP_CTR_TX; // preserve CTR_TX (clears on writing 0)
-  pcd_set_endpoint(USBx, bEpIdx, regVal);
-}
-
 TU_ATTR_ALWAYS_INLINE static inline void pcd_clear_tx_ep_ctr(USB_TypeDef * USBx, uint32_t bEpIdx) {
   uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
   regVal &= USB_EPREG_MASK;
@@ -310,6 +293,10 @@ TU_ATTR_ALWAYS_INLINE static inline uint32_t ep_add_dtog(uint32_t reg, tusb_dir_
   return reg ^ (state << (USB_EP_DTOG_TX_Pos + (dir == TUSB_DIR_IN ? 0 : 8)));
 }
 
+TU_ATTR_ALWAYS_INLINE static inline bool ep_is_iso(uint32_t reg) {
+  return (reg & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS;
+}
+
 /**
   * @brief  sets the status for tx transfer (bits STAT_TX[1:0]).
   * @param  USBx USB peripheral instance register address.
@@ -341,54 +328,6 @@ TU_ATTR_ALWAYS_INLINE static inline void pcd_set_ep_rx_status(USB_TypeDef * USBx
   pcd_set_endpoint(USBx, bEpIdx, regVal);
 }
 
-//TU_ATTR_ALWAYS_INLINE static inline uint32_t pcd_get_ep_rx_status(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-//  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-//  return (regVal & USB_EPRX_STAT) >> (12u);
-//}
-
-TU_ATTR_ALWAYS_INLINE static inline void pcd_rx_dtog(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  regVal &= USB_EPREG_MASK;
-  regVal |= USB_EP_CTR_RX|USB_EP_CTR_TX|USB_EP_DTOG_RX;
-  pcd_set_endpoint(USBx, bEpIdx, regVal);
-}
-
-TU_ATTR_ALWAYS_INLINE static inline void pcd_tx_dtog(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  regVal &= USB_EPREG_MASK;
-  regVal |= USB_EP_CTR_RX|USB_EP_CTR_TX|USB_EP_DTOG_TX;
-  pcd_set_endpoint(USBx, bEpIdx, regVal);
-}
-
-TU_ATTR_ALWAYS_INLINE static inline void pcd_clear_rx_dtog(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  if((regVal & USB_EP_DTOG_RX) != 0) {
-    pcd_rx_dtog(USBx,bEpIdx);
-  }
-}
-
-TU_ATTR_ALWAYS_INLINE static inline void pcd_clear_tx_dtog(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-  if((regVal & USB_EP_DTOG_TX) != 0) {
-    pcd_tx_dtog(USBx,bEpIdx);
-  }
-}
-
-//TU_ATTR_ALWAYS_INLINE static inline void pcd_set_ep_kind(USB_TypeDef * USBx,  uint32_t bEpIdx) {
-//  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-//  regVal |= USB_EP_KIND;
-//  regVal &= USB_EPREG_MASK;
-//  regVal |= USB_EP_CTR_RX|USB_EP_CTR_TX;
-//  pcd_set_endpoint(USBx, bEpIdx, regVal);
-//}
-//
-//TU_ATTR_ALWAYS_INLINE static inline void pcd_clear_ep_kind(USB_TypeDef * USBx, uint32_t bEpIdx) {
-//  uint32_t regVal = pcd_get_endpoint(USBx, bEpIdx);
-//  regVal &= USB_EPKIND_MASK;
-//  regVal |= USB_EP_CTR_RX|USB_EP_CTR_TX;
-//  pcd_set_endpoint(USBx, bEpIdx, regVal);
-//}
-
 #ifdef __cplusplus
  }
 #endif