fix(heap): revert DMA pool MALLOC_CAP_DEFAULT caps

docs/en/api-guides/external-ram.rst

@@ -104,14 +104,7 @@ An additional configuration item, :ref:`CONFIG_SPIRAM_MALLOC_ALWAYSINTERNAL`, ca
 
 If a suitable block of preferred internal/external memory is not available, the allocator will try the other type of memory.
 
-Because some buffers can only be allocated in internal memory, a second configuration item :ref:`CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL` reserves a pool of internal DMA-capable memory at startup (in ``main_task``, after PSRAM is initialized). The pool is malloc from the regular internal heaps and re-registered as separate heap pool.
-
-The reserved pool uses the heap capability priority mechanism:
-
-- **Medium priority** — ``MALLOC_CAP_DMA | MALLOC_CAP_INTERNAL``: explicit ``heap_caps_malloc()`` requests with these flags are preferentially served from this pool.
-- **Low priority** — ``MALLOC_CAP_DEFAULT``: ``malloc()`` may use the pool only after other internal heaps with higher-priority ``MALLOC_CAP_DEFAULT`` are exhausted.
-
-Therefore, under normal conditions ``malloc()`` does not allocate from this pool, but it can fall back to it as a last resort before allocation fails entirely.
+Because some buffers can only be allocated in internal memory, a second configuration item :ref:`CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL` defines a pool of internal memory which is reserved for *only* explicitly internal allocations (such as memory for DMA use). Regular ``malloc()`` will not allocate from this pool. The :ref:`MALLOC_CAP_DMA <dma-capable-memory>` and ``MALLOC_CAP_INTERNAL`` flags can be used to allocate memory from this pool.
 
 .. _external_ram_config_bss:
 

docs/zh_CN/api-guides/external-ram.rst

@@ -104,14 +104,7 @@ ESP-IDF 启动过程中，片外 RAM 被映射到数据虚拟地址空间，该
 
 如果优先考虑的内部或外部存储器中没有可用的存储块，分配程序则会选择其他类型存储。
 
-由于有些内存缓冲器仅可在内部存储器中分配，因此需要使用第二个配置项 :ref:`CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL` 在启动阶段（PSRAM 初始化完成后，于 ``main_task`` 中）预留一块内部 DMA 可用内存池。该内存从常规内部堆中分配出，并重新注册为独立的内存池。
-
-预留池通过堆能力优先级机制管理：
-
-- **中优先级** — ``MALLOC_CAP_DMA | MALLOC_CAP_INTERNAL``：显式使用这些标志的 ``heap_caps_malloc()`` 请求会优先从此池分配。
-- **低优先级** — ``MALLOC_CAP_DEFAULT``：仅当其他具有更高优先级 ``MALLOC_CAP_DEFAULT`` 的内部堆耗尽后，``malloc()`` 才会回退使用此池。
-
-因此，在正常情况下 ``malloc()`` 不会从该池分配；仅当其他内部内存耗尽后，``malloc()`` 才会将其作为最后的回退来源以避免分配完全失败。
+由于有些内存缓冲器仅可在内部存储器中分配，因此需要使用第二个配置项 :ref:`CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL` 定义一个内部内存池，仅限显式的内部存储器分配使用（例如用于 DMA 的存储器）。常规 ``malloc()`` 将不会从该池中分配，但可以使用 :ref:`MALLOC_CAP_DMA <dma-capable-memory>` 和 ``MALLOC_CAP_INTERNAL`` 标志从该池中分配存储器。
 
 .. _external_ram_config_bss: