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docs: dma-api: remove duplicate description of the DMA pool API 

Move the DMA pool API documentation from Memory Management APIs to
dma-api.rst, replacing the outdated duplicate description there.

Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250627101015.1600042-6-ptesarik@suse.com
This commit is contained in:
Petr Tesarik 2025-06-27 12:10:12 +02:00 committed by Jonathan Corbet
parent fc9a099567
commit 61043d0995
2 changed files with 3 additions and 67 deletions
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62
Documentation/core-api/dma-api.rst
View File

@ -83,66 +83,10 @@ much like a struct kmem_cache, except that they use the DMA-coherent allocator,
not __get_free_pages(). Also, they understand common hardware constraints
for alignment, like queue heads needing to be aligned on N-byte boundaries.
.. kernel-doc:: mm/dmapool.c
:export:
::
struct dma_pool *
dma_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t alloc);
dma_pool_create() initializes a pool of DMA-coherent buffers
for use with a given device. It must be called in a context which
can sleep.
The "name" is for diagnostics (like a struct kmem_cache name); dev and size
are like what you'd pass to dma_alloc_coherent(). The device's hardware
alignment requirement for this type of data is "align" (which is expressed
in bytes, and must be a power of two). If your device has no boundary
crossing restrictions, pass 0 for alloc; passing 4096 says memory allocated
from this pool must not cross 4KByte boundaries.
::
void *
dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
dma_addr_t *handle)
Wraps dma_pool_alloc() and also zeroes the returned memory if the
allocation attempt succeeded.
::
void *
dma_pool_alloc(struct dma_pool *pool, gfp_t gfp_flags,
dma_addr_t *dma_handle);
This allocates memory from the pool; the returned memory will meet the
size and alignment requirements specified at creation time. Pass
GFP_ATOMIC to prevent blocking, or if it's permitted (not
in_interrupt, not holding SMP locks), pass GFP_KERNEL to allow
blocking. Like dma_alloc_coherent(), this returns two values: an
address usable by the CPU, and the DMA address usable by the pool's
device.
::
void
dma_pool_free(struct dma_pool *pool, void *vaddr,
dma_addr_t addr);
This puts memory back into the pool. The pool is what was passed to
dma_pool_alloc(); the CPU (vaddr) and DMA addresses are what
were returned when that routine allocated the memory being freed.
::
void
dma_pool_destroy(struct dma_pool *pool);
dma_pool_destroy() frees the resources of the pool. It must be
called in a context which can sleep. Make sure you've freed all allocated
memory back to the pool before you destroy it.
.. kernel-doc:: include/linux/dmapool.h
Part Ic - DMA addressing limitations

8
Documentation/core-api/mm-api.rst
View File

@ -91,14 +91,6 @@ Memory pools
.. kernel-doc:: mm/mempool.c
:export:
DMA pools
=========
.. kernel-doc:: mm/dmapool.c
:export:
.. kernel-doc:: include/linux/dmapool.h
More Memory Management Functions
================================