diff --git a/hw/bsp/rp2040/family.cmake b/hw/bsp/rp2040/family.cmake
index 5dba9dc39..f83120567 100644
--- a/hw/bsp/rp2040/family.cmake
+++ b/hw/bsp/rp2040/family.cmake
@@ -116,6 +116,7 @@ if (NOT TARGET _rp2040_family_inclusion_marker)
 
 	target_compile_definitions(tinyusb_additions INTERFACE
 		PICO_RP2040_USB_DEVICE_ENUMERATION_FIX=1
+		PICO_RP2040_USB_DEVICE_UFRAME_FIX=1
 	)
 
 	if(DEFINED LOG)
diff --git a/src/portable/raspberrypi/rp2040/dcd_rp2040.c b/src/portable/raspberrypi/rp2040/dcd_rp2040.c
index 4952d29b1..b5fa90c92 100644
--- a/src/portable/raspberrypi/rp2040/dcd_rp2040.c
+++ b/src/portable/raspberrypi/rp2040/dcd_rp2040.c
@@ -46,9 +46,6 @@
 /* Low level controller
  *------------------------------------------------------------------*/
 
-#define usb_hw_set hw_set_alias(usb_hw)
-#define usb_hw_clear hw_clear_alias(usb_hw)
-
 // Init these in dcd_init
 static uint8_t *next_buffer_ptr;
 
@@ -247,104 +244,133 @@ static void __tusb_irq_path_func(reset_non_control_endpoints)(void)
 
 static void __tusb_irq_path_func(dcd_rp2040_irq)(void)
 {
-    uint32_t const status = usb_hw->ints;
-    uint32_t handled = 0;
+  uint32_t const status = usb_hw->ints;
+  uint32_t handled = 0;
 
-    if (status & USB_INTF_DEV_SOF_BITS)
+  if ( status & USB_INTF_DEV_SOF_BITS )
+  {
+    bool keep_sof_alive = false;
+
+    handled |= USB_INTF_DEV_SOF_BITS;
+
+#if TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
+    // Errata 15 workaround for Device Bulk-In endpoint
+    e15_last_sof = time_us_32();
+
+    for ( uint8_t i = 0; i < USB_MAX_ENDPOINTS; i++ )
     {
-      handled |= USB_INTF_DEV_SOF_BITS;
+      struct hw_endpoint * ep = hw_endpoint_get_by_num(i, TUSB_DIR_IN);
 
-      // disable SOF interrupt if it is used for RESUME in remote wakeup
-      if (!_sof_enable) usb_hw_clear->inte = USB_INTS_DEV_SOF_BITS;
+      // Active Bulk IN endpoint requires SOF
+      if ( (ep->transfer_type == TUSB_XFER_BULK) && ep->active )
+      {
+        keep_sof_alive = true;
 
-      dcd_event_sof(0, usb_hw->sof_rd & USB_SOF_RD_BITS, true);
-    }
+        hw_endpoint_lock_update(ep, 1);
 
-    // xfer events are handled before setup req. So if a transfer completes immediately
-    // before closing the EP, the events will be delivered in same order.
-    if (status & USB_INTS_BUFF_STATUS_BITS)
-    {
-        handled |= USB_INTS_BUFF_STATUS_BITS;
-        hw_handle_buff_status();
-    }
-
-    if (status & USB_INTS_SETUP_REQ_BITS)
-    {
-        handled |= USB_INTS_SETUP_REQ_BITS;
-        uint8_t const *setup = (uint8_t const *)&usb_dpram->setup_packet;
-
-        // reset pid to both 1 (data and ack)
-        reset_ep0_pid();
-
-        // Pass setup packet to tiny usb
-        dcd_event_setup_received(0, setup, true);
-        usb_hw_clear->sie_status = USB_SIE_STATUS_SETUP_REC_BITS;
-    }
-
-#if FORCE_VBUS_DETECT == 0
-    // Since we force VBUS detect On, device will always think it is connected and
-    // couldn't distinguish between disconnect and suspend
-    if (status & USB_INTS_DEV_CONN_DIS_BITS)
-    {
-        handled |= USB_INTS_DEV_CONN_DIS_BITS;
-
-        if ( usb_hw->sie_status & USB_SIE_STATUS_CONNECTED_BITS )
+        // Deferred enable?
+        if ( ep->pending )
         {
-          // Connected: nothing to do
-        }else
-        {
-          // Disconnected
-          dcd_event_bus_signal(0, DCD_EVENT_UNPLUGGED, true);
+          ep->pending = 0;
+          hw_endpoint_start_next_buffer(ep);
         }
 
-        usb_hw_clear->sie_status = USB_SIE_STATUS_CONNECTED_BITS;
+        hw_endpoint_lock_update(ep, -1);
+      }
     }
 #endif
 
-    // SE0 for 2.5 us or more (will last at least 10ms)
-    if (status & USB_INTS_BUS_RESET_BITS)
+    // disable SOF interrupt if it is used for RESUME in remote wakeup
+    if ( !keep_sof_alive && !_sof_enable ) usb_hw_clear->inte = USB_INTS_DEV_SOF_BITS;
+
+    dcd_event_sof(0, usb_hw->sof_rd & USB_SOF_RD_BITS, true);
+  }
+
+  // xfer events are handled before setup req. So if a transfer completes immediately
+  // before closing the EP, the events will be delivered in same order.
+  if ( status & USB_INTS_BUFF_STATUS_BITS )
+  {
+    handled |= USB_INTS_BUFF_STATUS_BITS;
+    hw_handle_buff_status();
+  }
+
+  if ( status & USB_INTS_SETUP_REQ_BITS )
+  {
+    handled |= USB_INTS_SETUP_REQ_BITS;
+    uint8_t const * setup = (uint8_t const*) &usb_dpram->setup_packet;
+
+    // reset pid to both 1 (data and ack)
+    reset_ep0_pid();
+
+    // Pass setup packet to tiny usb
+    dcd_event_setup_received(0, setup, true);
+    usb_hw_clear->sie_status = USB_SIE_STATUS_SETUP_REC_BITS;
+  }
+
+#if FORCE_VBUS_DETECT == 0
+  // Since we force VBUS detect On, device will always think it is connected and
+  // couldn't distinguish between disconnect and suspend
+  if (status & USB_INTS_DEV_CONN_DIS_BITS)
+  {
+    handled |= USB_INTS_DEV_CONN_DIS_BITS;
+
+    if ( usb_hw->sie_status & USB_SIE_STATUS_CONNECTED_BITS )
     {
-        pico_trace("BUS RESET\n");
+      // Connected: nothing to do
+    }else
+    {
+      // Disconnected
+      dcd_event_bus_signal(0, DCD_EVENT_UNPLUGGED, true);
+    }
 
-        handled |= USB_INTS_BUS_RESET_BITS;
+    usb_hw_clear->sie_status = USB_SIE_STATUS_CONNECTED_BITS;
+  }
+#endif
 
-        usb_hw->dev_addr_ctrl = 0;
-        reset_non_control_endpoints();
-        dcd_event_bus_reset(0, TUSB_SPEED_FULL, true);
-        usb_hw_clear->sie_status = USB_SIE_STATUS_BUS_RESET_BITS;
+  // SE0 for 2.5 us or more (will last at least 10ms)
+  if ( status & USB_INTS_BUS_RESET_BITS )
+  {
+    pico_trace("BUS RESET\n");
+
+    handled |= USB_INTS_BUS_RESET_BITS;
+
+    usb_hw->dev_addr_ctrl = 0;
+    reset_non_control_endpoints();
+    dcd_event_bus_reset(0, TUSB_SPEED_FULL, true);
+    usb_hw_clear->sie_status = USB_SIE_STATUS_BUS_RESET_BITS;
 
 #if TUD_OPT_RP2040_USB_DEVICE_ENUMERATION_FIX
-        // Only run enumeration walk-around if pull up is enabled
-        if ( usb_hw->sie_ctrl & USB_SIE_CTRL_PULLUP_EN_BITS ) rp2040_usb_device_enumeration_fix();
+    // Only run enumeration workaround if pull up is enabled
+    if ( usb_hw->sie_ctrl & USB_SIE_CTRL_PULLUP_EN_BITS ) rp2040_usb_device_enumeration_fix();
 #endif
-    }
+  }
 
-    /* Note from pico datasheet 4.1.2.6.4 (v1.2)
-     * If you enable the suspend interrupt, it is likely you will see a suspend interrupt when
-     * the device is first connected but the bus is idle. The bus can be idle for a few ms before
-     * the host begins sending start of frame packets. You will also see a suspend interrupt
-     * when the device is disconnected if you do not have a VBUS detect circuit connected. This is
-     * because without VBUS detection, it is impossible to tell the difference between
-     * being disconnected and suspended.
-     */
-    if (status & USB_INTS_DEV_SUSPEND_BITS)
-    {
-        handled |= USB_INTS_DEV_SUSPEND_BITS;
-        dcd_event_bus_signal(0, DCD_EVENT_SUSPEND, true);
-        usb_hw_clear->sie_status = USB_SIE_STATUS_SUSPENDED_BITS;
-    }
+  /* Note from pico datasheet 4.1.2.6.4 (v1.2)
+   * If you enable the suspend interrupt, it is likely you will see a suspend interrupt when
+   * the device is first connected but the bus is idle. The bus can be idle for a few ms before
+   * the host begins sending start of frame packets. You will also see a suspend interrupt
+   * when the device is disconnected if you do not have a VBUS detect circuit connected. This is
+   * because without VBUS detection, it is impossible to tell the difference between
+   * being disconnected and suspended.
+   */
+  if ( status & USB_INTS_DEV_SUSPEND_BITS )
+  {
+    handled |= USB_INTS_DEV_SUSPEND_BITS;
+    dcd_event_bus_signal(0, DCD_EVENT_SUSPEND, true);
+    usb_hw_clear->sie_status = USB_SIE_STATUS_SUSPENDED_BITS;
+  }
 
-    if (status & USB_INTS_DEV_RESUME_FROM_HOST_BITS)
-    {
-        handled |= USB_INTS_DEV_RESUME_FROM_HOST_BITS;
-        dcd_event_bus_signal(0, DCD_EVENT_RESUME, true);
-        usb_hw_clear->sie_status = USB_SIE_STATUS_RESUME_BITS;
-    }
+  if ( status & USB_INTS_DEV_RESUME_FROM_HOST_BITS )
+  {
+    handled |= USB_INTS_DEV_RESUME_FROM_HOST_BITS;
+    dcd_event_bus_signal(0, DCD_EVENT_RESUME, true);
+    usb_hw_clear->sie_status = USB_SIE_STATUS_RESUME_BITS;
+  }
 
-    if (status ^ handled)
-    {
-        panic("Unhandled IRQ 0x%x\n", (uint) (status ^ handled));
-    }
+  if ( status ^ handled )
+  {
+    panic("Unhandled IRQ 0x%x\n", (uint) (status ^ handled));
+  }
 }
 
 #define USB_INTS_ERROR_BITS ( \
@@ -452,7 +478,11 @@ void dcd_sof_enable(uint8_t rhport, bool en)
     usb_hw_set->inte = USB_INTS_DEV_SOF_BITS;
   }else
   {
+    // Don't clear immediately if the SOF workaround is in use.
+    // The SOF handler will conditionally disable the interrupt.
+#if !TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
     usb_hw_clear->inte = USB_INTS_DEV_SOF_BITS;
+#endif
   }
 }
 
diff --git a/src/portable/raspberrypi/rp2040/hcd_rp2040.c b/src/portable/raspberrypi/rp2040/hcd_rp2040.c
index 9e6bdad44..28abd7939 100644
--- a/src/portable/raspberrypi/rp2040/hcd_rp2040.c
+++ b/src/portable/raspberrypi/rp2040/hcd_rp2040.c
@@ -56,9 +56,6 @@ static_assert(PICO_USB_HOST_INTERRUPT_ENDPOINTS <= USB_MAX_ENDPOINTS, "");
 static struct hw_endpoint ep_pool[1 + PICO_USB_HOST_INTERRUPT_ENDPOINTS];
 #define epx (ep_pool[0])
 
-#define usb_hw_set   hw_set_alias(usb_hw)
-#define usb_hw_clear hw_clear_alias(usb_hw)
-
 // Flags we set by default in sie_ctrl (we add other bits on top)
 enum {
   SIE_CTRL_BASE = USB_SIE_CTRL_SOF_EN_BITS      | USB_SIE_CTRL_KEEP_ALIVE_EN_BITS |
diff --git a/src/portable/raspberrypi/rp2040/rp2040_usb.c b/src/portable/raspberrypi/rp2040/rp2040_usb.c
index 5c7645902..df05697fe 100644
--- a/src/portable/raspberrypi/rp2040/rp2040_usb.c
+++ b/src/portable/raspberrypi/rp2040/rp2040_usb.c
@@ -32,20 +32,25 @@
 #include <stdlib.h>
 #include "rp2040_usb.h"
 
+//--------------------------------------------------------------------+
+// MACRO CONSTANT TYPEDEF PROTOTYPE
+//--------------------------------------------------------------------+
+
 // Direction strings for debug
 const char *ep_dir_string[] = {
         "out",
         "in",
 };
 
-TU_ATTR_ALWAYS_INLINE static inline void _hw_endpoint_lock_update(__unused struct hw_endpoint * ep, __unused int delta) {
-    // todo add critsec as necessary to prevent issues between worker and IRQ...
-    //  note that this is perhaps as simple as disabling IRQs because it would make
-    //  sense to have worker and IRQ on same core, however I think using critsec is about equivalent.
-}
-
 static void _hw_endpoint_xfer_sync(struct hw_endpoint *ep);
-static void _hw_endpoint_start_next_buffer(struct hw_endpoint *ep);
+
+#if TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
+  static bool e15_is_bulkin_ep(struct hw_endpoint *ep);
+  static bool e15_is_critical_frame_period(struct hw_endpoint *ep);
+#else
+  #define e15_is_bulkin_ep(x)             (false)
+  #define e15_is_critical_frame_period(x) (false)
+#endif
 
 // if usb hardware is in host mode
 TU_ATTR_ALWAYS_INLINE static inline bool is_host_mode(void)
@@ -54,7 +59,7 @@ TU_ATTR_ALWAYS_INLINE static inline bool is_host_mode(void)
 }
 
 //--------------------------------------------------------------------+
-//
+// Implementation
 //--------------------------------------------------------------------+
 
 void rp2040_usb_init(void)
@@ -87,12 +92,15 @@ void __tusb_irq_path_func(hw_endpoint_reset_transfer)(struct hw_endpoint *ep)
   ep->user_buf = 0;
 }
 
-void __tusb_irq_path_func(_hw_endpoint_buffer_control_update32)(struct hw_endpoint *ep, uint32_t and_mask, uint32_t or_mask) {
+void __tusb_irq_path_func(_hw_endpoint_buffer_control_update32)(struct hw_endpoint *ep, uint32_t and_mask, uint32_t or_mask)
+{
   uint32_t value = 0;
+
   if ( and_mask )
   {
     value = *ep->buffer_control & and_mask;
   }
+
   if ( or_mask )
   {
     value |= or_mask;
@@ -118,6 +126,7 @@ void __tusb_irq_path_func(_hw_endpoint_buffer_control_update32)(struct hw_endpoi
 #endif
     }
   }
+
   *ep->buffer_control = value;
 }
 
@@ -157,7 +166,7 @@ static uint32_t __tusb_irq_path_func(prepare_ep_buffer)(struct hw_endpoint *ep,
 }
 
 // Prepare buffer control register value
-static void __tusb_irq_path_func(_hw_endpoint_start_next_buffer)(struct hw_endpoint *ep)
+void __tusb_irq_path_func(hw_endpoint_start_next_buffer)(struct hw_endpoint *ep)
 {
   uint32_t ep_ctrl = *ep->endpoint_control;
 
@@ -201,7 +210,7 @@ static void __tusb_irq_path_func(_hw_endpoint_start_next_buffer)(struct hw_endpo
 
 void hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len)
 {
-  _hw_endpoint_lock_update(ep, 1);
+  hw_endpoint_lock_update(ep, 1);
 
   if ( ep->active )
   {
@@ -218,8 +227,20 @@ void hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t to
   ep->active        = true;
   ep->user_buf      = buffer;
 
-  _hw_endpoint_start_next_buffer(ep);
-  _hw_endpoint_lock_update(ep, -1);
+  if ( e15_is_bulkin_ep(ep) )
+  {
+    usb_hw_set->inte = USB_INTS_DEV_SOF_BITS;
+  }
+
+  if ( e15_is_critical_frame_period(ep) )
+  {
+    ep->pending = 1;
+  } else
+  {
+    hw_endpoint_start_next_buffer(ep);
+  }
+
+  hw_endpoint_lock_update(ep, -1);
 }
 
 // sync endpoint buffer and return transferred bytes
@@ -312,7 +333,8 @@ static void __tusb_irq_path_func(_hw_endpoint_xfer_sync) (struct hw_endpoint *ep
 // Returns true if transfer is complete
 bool __tusb_irq_path_func(hw_endpoint_xfer_continue)(struct hw_endpoint *ep)
 {
-  _hw_endpoint_lock_update(ep, 1);
+  hw_endpoint_lock_update(ep, 1);
+
   // Part way through a transfer
   if (!ep->active)
   {
@@ -329,17 +351,75 @@ bool __tusb_irq_path_func(hw_endpoint_xfer_continue)(struct hw_endpoint *ep)
     pico_trace("Completed transfer of %d bytes on ep %d %s\n",
                ep->xferred_len, tu_edpt_number(ep->ep_addr), ep_dir_string[tu_edpt_dir(ep->ep_addr)]);
     // Notify caller we are done so it can notify the tinyusb stack
-    _hw_endpoint_lock_update(ep, -1);
+    hw_endpoint_lock_update(ep, -1);
     return true;
   }
   else
   {
-    _hw_endpoint_start_next_buffer(ep);
+    if ( e15_is_critical_frame_period(ep) )
+    {
+      ep->pending = 1;
+    } else
+    {
+      hw_endpoint_start_next_buffer(ep);
+    }
   }
 
-  _hw_endpoint_lock_update(ep, -1);
+  hw_endpoint_lock_update(ep, -1);
   // More work to do
   return false;
 }
 
+//--------------------------------------------------------------------+
+// Errata 15
+//--------------------------------------------------------------------+
+
+#if TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
+
+/* Don't mark IN buffers as available during the last 200us of a full-speed
+   frame. This avoids a situation seen with the USB2.0 hub on a Raspberry
+   Pi 4 where a late IN token before the next full-speed SOF can cause port
+   babble and a corrupt ACK packet. The nature of the data corruption has a
+   chance to cause device lockup.
+
+   Use the next SOF to mark delayed buffers as available. This reduces
+   available Bulk IN bandwidth by approximately 20%, and requires that the
+   SOF interrupt is enabled while these transfers are ongoing.
+
+   Inherit the top-level enable from the corresponding Pico-SDK flag.
+   Applications that will not use the device in a situation where it could
+   be plugged into a Pi 4 or Pi 400 (for example, when directly connected
+   to a commodity hub or other host) can turn off the flag in the SDK.
+*/
+
+volatile uint32_t e15_last_sof = 0;
+
+// check if Errata 15 is needed for this endpoint i.e device bulk-in
+static bool __tusb_irq_path_func(e15_is_bulkin_ep) (struct hw_endpoint *ep)
+{
+  return (!is_host_mode() && tu_edpt_dir(ep->ep_addr) == TUSB_DIR_IN &&
+          ep->transfer_type == TUSB_XFER_BULK);
+}
+
+// check if we need to apply Errata 15 workaround : i.e
+// Endpoint is BULK IN and is currently in critical frame period i.e 20% of last usb frame
+static bool __tusb_irq_path_func(e15_is_critical_frame_period) (struct hw_endpoint *ep)
+{
+  TU_VERIFY(e15_is_bulkin_ep(ep));
+
+  /* Avoid the last 200us (uframe 6.5-7) of a frame, up to the EOF2 point.
+   * The device state machine cannot recover from receiving an incorrect PID
+   * when it is expecting an ACK.
+   */
+  uint32_t delta = time_us_32() - e15_last_sof;
+  if (delta < 800 || delta > 998) {
+    return false;
+  }
+  TU_LOG(3, "Avoiding sof %u now %lu last %lu\n", (usb_hw->sof_rd + 1) & USB_SOF_RD_BITS, time_us_32(), e15_last_sof);
+  return true;
+}
+
+#endif
+
+
 #endif
diff --git a/src/portable/raspberrypi/rp2040/rp2040_usb.h b/src/portable/raspberrypi/rp2040/rp2040_usb.h
index b65d32fd4..a06407f23 100644
--- a/src/portable/raspberrypi/rp2040/rp2040_usb.h
+++ b/src/portable/raspberrypi/rp2040/rp2040_usb.h
@@ -11,11 +11,21 @@
 #include "hardware/structs/usb.h"
 #include "hardware/irq.h"
 #include "hardware/resets.h"
+#include "hardware/timer.h"
 
 #if defined(PICO_RP2040_USB_DEVICE_ENUMERATION_FIX) && !defined(TUD_OPT_RP2040_USB_DEVICE_ENUMERATION_FIX)
 #define TUD_OPT_RP2040_USB_DEVICE_ENUMERATION_FIX PICO_RP2040_USB_DEVICE_ENUMERATION_FIX
 #endif
 
+#if defined(PICO_RP2040_USB_DEVICE_UFRAME_FIX) && !defined(TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX)
+#define TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX PICO_RP2040_USB_DEVICE_UFRAME_FIX
+#endif
+
+#if TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
+#undef PICO_RP2040_USB_FAST_IRQ
+#define PICO_RP2040_USB_FAST_IRQ 1
+#endif
+
 #ifndef PICO_RP2040_USB_FAST_IRQ
 #define PICO_RP2040_USB_FAST_IRQ 0
 #endif
@@ -26,6 +36,9 @@
 #define __tusb_irq_path_func(x) x
 #endif
 
+#define usb_hw_set hw_set_alias(usb_hw)
+#define usb_hw_clear hw_clear_alias(usb_hw)
+
 #define pico_info(...)  TU_LOG(2, __VA_ARGS__)
 #define pico_trace(...) TU_LOG(3, __VA_ARGS__)
 
@@ -38,7 +51,7 @@ typedef struct hw_endpoint
     // Transfer direction (i.e. IN is rx for host but tx for device)
     // allows us to common up transfer functions
     bool rx;
-    
+
     uint8_t ep_addr;
     uint8_t next_pid;
 
@@ -51,20 +64,25 @@ typedef struct hw_endpoint
     // Buffer pointer in usb dpram
     uint8_t *hw_data_buf;
 
-    // Current transfer information
-    bool active;
-    uint16_t remaining_len;
-    uint16_t xferred_len;
-
     // User buffer in main memory
     uint8_t *user_buf;
 
+    // Current transfer information
+    uint16_t remaining_len;
+    uint16_t xferred_len;
+
     // Data needed from EP descriptor
     uint16_t wMaxPacketSize;
 
+    // Endpoint is in use
+    bool active;
+
     // Interrupt, bulk, etc
     uint8_t transfer_type;
-    
+
+    // Transfer scheduled but not active
+    uint8_t pending;
+
 #if CFG_TUH_ENABLED
     // Only needed for host
     uint8_t dev_addr;
@@ -72,13 +90,25 @@ typedef struct hw_endpoint
     // If interrupt endpoint
     uint8_t interrupt_num;
 #endif
+
 } hw_endpoint_t;
 
+#if TUD_OPT_RP2040_USB_DEVICE_UFRAME_FIX
+extern volatile uint32_t e15_last_sof;
+#endif
+
 void rp2040_usb_init(void);
 
 void hw_endpoint_xfer_start(struct hw_endpoint *ep, uint8_t *buffer, uint16_t total_len);
 bool hw_endpoint_xfer_continue(struct hw_endpoint *ep);
 void hw_endpoint_reset_transfer(struct hw_endpoint *ep);
+void hw_endpoint_start_next_buffer(struct hw_endpoint *ep);
+
+TU_ATTR_ALWAYS_INLINE static inline void hw_endpoint_lock_update(__unused struct hw_endpoint * ep, __unused int delta) {
+  // todo add critsec as necessary to prevent issues between worker and IRQ...
+  //  note that this is perhaps as simple as disabling IRQs because it would make
+  //  sense to have worker and IRQ on same core, however I think using critsec is about equivalent.
+}
 
 void _hw_endpoint_buffer_control_update32(struct hw_endpoint *ep, uint32_t and_mask, uint32_t or_mask);