usbd: hold RX_PENDING in every build, not only with OSAL_MUTEX_REQUIRED

One state bit and one code path regardless of OS/core config, so a class driver
that claims an OUT endpoint from xfer_cb without consuming misbehaves the same
way on bare-metal as under an RTOS, and test_usbd covers it without forcing
TUP_MCU_MULTIPLE_CORE.

src/common/tusb_private.h

diff --git a/src/common/tusb_private.h b/src/common/tusb_private.h
index e333651..f45273f 100644
--- a/src/common/tusb_private.h
+++ b/src/common/tusb_private.h
@@ -145,7 +145,7 @@
 // Start an usb transfer if endpoint is not busy
 uint32_t tu_edpt_stream_read_xfer(tu_edpt_stream_t *s);
 
-#if CFG_TUD_ENABLED && OSAL_MUTEX_REQUIRED
+#if CFG_TUD_ENABLED
 // Release an OUT endpoint's RX_PENDING hold once its buffer is consumed, allowing it to be claimed
 void usbd_edpt_rx_consume(uint8_t rhport, uint8_t ep_addr);
 #else

src/device/usbd.c

diff --git a/src/device/usbd.c b/src/device/usbd.c
index 29ad0ee..6878208 100644
--- a/src/device/usbd.c
+++ b/src/device/usbd.c
@@ -403,10 +403,8 @@
 #if OSAL_MUTEX_REQUIRED
   static osal_mutex_def_t _ubsd_mutexdef;
   static osal_mutex_t _usbd_mutex;
-  #define USBD_RX_PENDING TU_EDPT_STATE_RX_PENDING
 #else
   #define _usbd_mutex   NULL
-  #define USBD_RX_PENDING 0u // no other task can claim an OUT endpoint while its xfer_cb runs
 #endif
 
 TU_ATTR_ALWAYS_INLINE static inline bool queue_event(dcd_event_t const * event, bool in_isr) {
@@ -763,7 +761,7 @@
 
         // Clear busy + claimed. A class OUT endpoint goes straight to RX_PENDING, so no other task can claim
         // and re-arm it before its buffer is consumed (#1292)
-        uint8_t const rx_pending = (0 != epnum && ep_dir == TUSB_DIR_OUT) ? USBD_RX_PENDING : 0u;
+        uint8_t const rx_pending = (0 != epnum && ep_dir == TUSB_DIR_OUT) ? TU_EDPT_STATE_RX_PENDING : 0u;
         _usbd_dev.ep_status[epnum][ep_dir] = (uint8_t) (
           (_usbd_dev.ep_status[epnum][ep_dir] & ~(TU_EDPT_STATE_BUSY | TU_EDPT_STATE_CLAIMED)) | rx_pending);
 
@@ -1598,7 +1596,6 @@
   return tu_edpt_release(&_usbd_dev.ep_status[epnum][dir], _usbd_mutex);
 }
 
-#if OSAL_MUTEX_REQUIRED
 void usbd_edpt_rx_consume(uint8_t rhport, uint8_t ep_addr) {
   (void) rhport;
 
@@ -1613,7 +1610,6 @@
   }
   (void) osal_mutex_unlock(_usbd_mutex);
 }
-#endif
 
 bool usbd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t* buffer, uint16_t total_bytes, bool is_isr) {
   rhport = _usbd_rhport;
@@ -1637,7 +1633,7 @@
   // Set busy first since the actual transfer can be complete before dcd_edpt_xfer()
   // could return and USBD task can preempt and clear the busy
   _usbd_dev.ep_status[epnum][dir] =
-    (uint8_t) ((_usbd_dev.ep_status[epnum][dir] & ~USBD_RX_PENDING) | TU_EDPT_STATE_BUSY);
+    (uint8_t) ((_usbd_dev.ep_status[epnum][dir] & ~TU_EDPT_STATE_RX_PENDING) | TU_EDPT_STATE_BUSY);
 
   if (dcd_edpt_xfer(rhport, ep_addr, buffer, total_bytes, is_isr)) {
     return true;
@@ -1671,7 +1667,7 @@
   // Set busy first since the actual transfer can be complete before dcd_edpt_xfer() could return
   // and usbd task can preempt and clear the busy
   _usbd_dev.ep_status[epnum][dir] =
-    (uint8_t) ((_usbd_dev.ep_status[epnum][dir] & ~USBD_RX_PENDING) | TU_EDPT_STATE_BUSY);
+    (uint8_t) ((_usbd_dev.ep_status[epnum][dir] & ~TU_EDPT_STATE_RX_PENDING) | TU_EDPT_STATE_BUSY);
 
   if (dcd_edpt_xfer_fifo(rhport, ep_addr, ff, total_bytes, is_isr)) {
     TU_LOG_USBD("OK\r\n");

src/device/usbd_pvt.h

diff --git a/src/device/usbd_pvt.h b/src/device/usbd_pvt.h
index d7cb9cc..a68e7f4 100644
--- a/src/device/usbd_pvt.h
+++ b/src/device/usbd_pvt.h
@@ -75,7 +75,7 @@
 // Claim an endpoint before submitting a transfer.
 // If caller does not make any transfer, it must release endpoint for others.
 // From an OUT xfer_cb, call usbd_edpt_rx_consume() (common/tusb_private.h) before claiming, or re-arm with
-// usbd_edpt_xfer() directly: with OSAL_MUTEX_REQUIRED the claim is refused until the buffer is consumed.
+// usbd_edpt_xfer() directly: the claim is refused until the buffer is consumed.
 bool usbd_edpt_claim(uint8_t rhport, uint8_t ep_addr);
 
 // Release claimed endpoint without submitting a transfer

test/unit-test/CMakeLists.txt

diff --git a/test/unit-test/CMakeLists.txt b/test/unit-test/CMakeLists.txt
index d58ad1a..06cff5b 100644
--- a/test/unit-test/CMakeLists.txt
+++ b/test/unit-test/CMakeLists.txt
@@ -120,7 +120,6 @@
   "${CEEDLING_WORKDIR}/../../src/tusb.c;${CEEDLING_WORKDIR}/../../src/device/usbd.c;${CEEDLING_WORKDIR}/../../src/common/tusb_fifo.c"
   "${CEEDLING_BUILD_DIR}/test/mocks/test_usbd/mock_dcd.c;${CEEDLING_BUILD_DIR}/test/mocks/test_usbd/mock_msc_device.c"
   )
-target_compile_definitions(test_usbd PRIVATE TUP_MCU_MULTIPLE_CORE=1)
 
 add_ceedling_test(
   test_msc_device

test/unit-test/project.yml

diff --git a/test/unit-test/project.yml b/test/unit-test/project.yml
index 02e341c..599dabc 100644
--- a/test/unit-test/project.yml
+++ b/test/unit-test/project.yml
@@ -132,8 +132,6 @@
       - CFG_TUD_EDPT_DEDICATED_HWFIFO=1
       - CFG_TUSB_FIFO_HWFIFO_DATA_STRIDE=6
       - CFG_TUSB_FIFO_HWFIFO_ADDR_STRIDE=0
-    :test_usbd:
-      - TUP_MCU_MULTIPLE_CORE=1 # OSAL_MUTEX_REQUIRED with osal_none, exercising the endpoint claim mutex
     :test_audio_host:
       - CFG_TUH_ENABLED=1
       - CFG_TUH_AUDIO=1