Commit ce00f7fe authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Linus Torvalds

Documentation: DMA-API-HOWTO.txt: rename ARCH_KMALLOC_MINALIGN to ARCH_DMA_MINALIGN

ARCH_KMALLOC_MINALIGN was renamed to ARCH_DMA_MINALIGN (the commit
a6eb9fe1).

ARCH_DMA_MINALIGN must be defined instead of ARCH_KMALLOC_MINALIGN to
ensure that kmalloc'ed buffer is DMA-safe.
Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b171aa27
...@@ -738,17 +738,17 @@ to "Closing". ...@@ -738,17 +738,17 @@ to "Closing".
CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
(including software IOMMU). (including software IOMMU).
2) ARCH_KMALLOC_MINALIGN 2) ARCH_DMA_MINALIGN
Architectures must ensure that kmalloc'ed buffer is Architectures must ensure that kmalloc'ed buffer is
DMA-safe. Drivers and subsystems depend on it. If an architecture DMA-safe. Drivers and subsystems depend on it. If an architecture
isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in
the CPU cache is identical to data in main memory), the CPU cache is identical to data in main memory),
ARCH_KMALLOC_MINALIGN must be set so that the memory allocator ARCH_DMA_MINALIGN must be set so that the memory allocator
makes sure that kmalloc'ed buffer doesn't share a cache line with makes sure that kmalloc'ed buffer doesn't share a cache line with
the others. See arch/arm/include/asm/cache.h as an example. the others. See arch/arm/include/asm/cache.h as an example.
Note that ARCH_KMALLOC_MINALIGN is about DMA memory alignment Note that ARCH_DMA_MINALIGN is about DMA memory alignment
constraints. You don't need to worry about the architecture data constraints. You don't need to worry about the architecture data
alignment constraints (e.g. the alignment constraints about 64-bit alignment constraints (e.g. the alignment constraints about 64-bit
objects). objects).
......
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