esp32: Increase NimBLE task stack size and overflow detection headroom.

The Python BLE IRQ handler will most likely run on the NimBLE task, so its
C stack must be large enough to accommodate reasonably complicated Python
code (eg a few call depths).  So increase this stack size.

Also increase the headroom from 1024 to 2048 bytes.  This is needed because
(1) the esp32 architecture uses a fair amount of stack in general; and (2)
by the time execution gets to setting the Python stack top via
`mp_stack_set_top()` in this interlock code, about 600 bytes of stack are
already used, which reduces the amount available for Python.

Fixes issue micropython#12349.

Signed-off-by: Damien George <damien@micropython.org>

extmod/modbluetooth.c

@@ -1274,7 +1274,7 @@ STATIC mp_obj_t invoke_irq_handler(uint16_t event,
     if (ts_orig == NULL) {
         mp_thread_set_state(&ts);
         mp_stack_set_top(&ts + 1); // need to include ts in root-pointer scan
-        mp_stack_set_limit(MICROPY_PY_BLUETOOTH_SYNC_EVENT_STACK_SIZE - 1024);
+        mp_stack_set_limit(MICROPY_PY_BLUETOOTH_SYNC_EVENT_STACK_SIZE);
         ts.gc_lock_depth = 0;
         ts.nlr_jump_callback_top = NULL;
         ts.mp_pending_exception = MP_OBJ_NULL;

ports/esp32/boards/sdkconfig.ble

@@ -14,3 +14,7 @@ CONFIG_BT_NIMBLE_MAX_CONNECTIONS=4
 CONFIG_BT_NIMBLE_PINNED_TO_CORE_0=n
 CONFIG_BT_NIMBLE_PINNED_TO_CORE_1=y
 CONFIG_BT_NIMBLE_PINNED_TO_CORE=1
+
+# Increase NimBLE task stack size from the default, because Python code
+# (BLE IRQ handlers) will most likely run on this task.
+CONFIG_BT_NIMBLE_TASK_STACK_SIZE=6144

ports/esp32/mpconfigport.h

@@ -95,7 +95,7 @@
 #define MICROPY_PY_BLUETOOTH                (1)
 #define MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS (1)
 #define MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS_WITH_INTERLOCK (1)
-#define MICROPY_PY_BLUETOOTH_SYNC_EVENT_STACK_SIZE (CONFIG_BT_NIMBLE_TASK_STACK_SIZE)
+#define MICROPY_PY_BLUETOOTH_SYNC_EVENT_STACK_SIZE (CONFIG_BT_NIMBLE_TASK_STACK_SIZE - 2048)
 #define MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE (1)
 #define MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING (1)
 #define MICROPY_BLUETOOTH_NIMBLE            (1)