dma-mapping: provide a better default ->get_required_mask

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Most dma_map_ops instances are IOMMUs that work perfectly fine in 32-bits
of IOVA space, and the generic direct mapping code already provides its
own routines that is intelligent based on the amount of memory actually
present.  Wire up the dma-direct routine for the ARM direct mapping code
as well, and otherwise default to the constant 32-bit mask.  This way
we only need to override it for the occasional odd IOMMU that requires
64-bit IOVA support, or IOMMU drivers that are more efficient if they
can fall back to the direct mapping.

Signed-off-by: Christoph Hellwig <hch@lst.de>

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This commit is contained in:

Christoph Hellwig 2019-08-06 15:01:38 +03:00

parent d9295532d5

commit 249baa5479

4 changed files with 14 additions and 27 deletions

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3

arch/arm/mm/dma-mapping.c

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7

arch/powerpc/platforms/ps3/system-bus.c

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1

arch/x86/kernel/amd_gart_64.c

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30

kernel/dma/mapping.c

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