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dma: compile-out DMA sync op calls when not used

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Some platforms do have DMA, but DMA there is always direct and coherent.
Currently, even on such platforms DMA sync operations are compiled and
called.
Add a new hidden Kconfig symbol, DMA_NEED_SYNC, and set it only when
either sync operations are needed or there is DMA ops or swiotlb
or DMA debug is enabled. Compile global dma_sync_*() and dma_need_sync()
only when it's set, otherwise provide empty inline stubs.
The change allows for future optimizations of DMA sync calls depending
on runtime conditions.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Alexander Lobakin
2024-05-07 13:20:20 +02:00
committed by Christoph Hellwig
parent 2650073f1b
commit fe7514b149
3 changed files with 50 additions and 39 deletions
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5
kernel/dma/Kconfig
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@@ -107,6 +107,11 @@ config DMA_BOUNCE_UNALIGNED_KMALLOC
bool
depends on SWIOTLB
config DMA_NEED_SYNC
def_bool ARCH_HAS_SYNC_DMA_FOR_DEVICE || ARCH_HAS_SYNC_DMA_FOR_CPU || \
ARCH_HAS_SYNC_DMA_FOR_CPU_ALL || DMA_API_DEBUG || DMA_OPS || \
SWIOTLB
config DMA_RESTRICTED_POOL
bool "DMA Restricted Pool"
depends on OF && OF_RESERVED_MEM && SWIOTLB