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change(system): heap_caps_alloc returns aligned memory if caps indicate a need for it

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The implicit promise of heap_alloc_caps() and friends is that the memory it
returns is fit for the purpose as requested in the caps field. Before
this commit, that did not happen; e.g. DMA-capable memory wass returned
from a correct region, but not aligned/sized to something the DMA subsystem
can handle.

This commit adds an API to the esp_mm component that is then used by the
heap component to adjust allocation alignment, caps and size dependent on
the hardware requirement of the requested allocation caps.
This commit is contained in:
Jeroen Domburg
2024-04-23 12:59:39 +08:00
parent 3f632df143
commit df4195062d
15 changed files with 323 additions and 53 deletions
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docs/en/api-reference/system/mem_alloc.rst
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@@ -107,7 +107,8 @@ Use the ``MALLOC_CAP_DMA`` flag to allocate memory which is suitable for use wit
.. only SOC_SPIRAM_SUPPORTED and not esp32::
The EDMA hardware feature allows DMA buffers to be placed in external PSRAM, but there may be additional alignment constraints. Consult the {IDF_TARGET_NAME} Technical Reference Manual for details. To allocate a DMA-capable external memory buffer, use the ``MALLOC_CAP_SPIRAM`` capabilities flag together with :cpp:func:`heap_caps_aligned_alloc` with the necessary alignment specified.
The EDMA hardware feature allows DMA buffers to be placed in external PSRAM, but there may be additional alignment constraints. Consult the {IDF_TARGET_NAME} Technical Reference Manual for details. To allocate a DMA-capable external memory buffer, use the ``MALLOC_CAP_SPIRAM | MALLOC_CAP_DMA`` capabilities flags; the heap allocator will take care of alignment requirements imposed by the cache and DMA subsystems. If a peripheral has additional alignment requirements, you can use :cpp:func:`heap_caps_aligned_alloc` with the necessary alignment specified.
.. _32-bit accessible memory: