[RFC 0/2] DMA-mapping & IOMMU - physically contiguous allocations

Marek Szyprowski m.szyprowski at samsung.com
Mon Oct 15 10:03:50 EDT 2012


Some devices, which have IOMMU, for some use cases might require to
allocate a buffers for DMA which is contiguous in physical memory. Such
use cases appears for example in DRM subsystem when one wants to improve
performance or use secure buffer protection.

I would like to ask if adding a new attribute, as proposed in this RFC
is a good idea? I feel that it might be an attribute just for a single
driver, but I would like to know your opinion. Should we look for other

Best regards
Marek Szyprowski
Samsung Poland R&D Center

Marek Szyprowski (2):
  common: DMA-mapping: add DMA_ATTR_FORCE_CONTIGUOUS attribute
  ARM: dma-mapping: add support for DMA_ATTR_FORCE_CONTIGUOUS attribute

 Documentation/DMA-attributes.txt |    9 +++++++++
 arch/arm/mm/dma-mapping.c        |   41 ++++++++++++++++++++++++++++++--------
 include/linux/dma-attrs.h        |    1 +
 3 files changed, 43 insertions(+), 8 deletions(-)


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