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由 Marek Szyprowski 提交于
IOMMU-aware dma_alloc_attrs() implementation allocates buffers in power-of-two chunks to improve performance and take advantage of large page mappings provided by some IOMMU hardware. However current code, due to a subtle bug, allocated those chunks in the smallest-to-largest order, what completely killed all the advantages of using larger than page chunks. If a 4KiB chunk has been mapped as a first chunk, the consecutive chunks are not aligned correctly to the power-of-two which match their size and IOMMU drivers were not able to use internal mappings of size other than the 4KiB (largest common denominator of alignment and chunk size). This patch fixes this issue by changing to the correct largest-to-smallest chunk size allocation sequence. Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
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