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dma-mapping: add a new dma_alloc_pages API

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This API is the equivalent of alloc_pages, except that the returned memory
is guaranteed to be DMA addressable by the passed in device.  The
implementation will also be used to provide a more sensible replacement
for DMA_ATTR_NON_CONSISTENT flag.

Additionally dma_alloc_noncoherent is switched over to use dma_alloc_pages
as its backend.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> (MIPS part)
This commit is contained in:
Christoph Hellwig
2020-09-01 13:34:33 +02:00
parent 5a84292271
commit efa70f2fdc
23 changed files with 206 additions and 37 deletions
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8
Documentation/core-api/dma-attributes.rst
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@@ -25,14 +25,6 @@ Since it is optional for platforms to implement DMA_ATTR_WRITE_COMBINE,
those that do not will simply ignore the attribute and exhibit default
behavior.
DMA_ATTR_NON_CONSISTENT
-----------------------
DMA_ATTR_NON_CONSISTENT lets the platform to choose to return either
consistent or non-consistent memory as it sees fit. By using this API,
you are guaranteeing to the platform that you have all the correct and
necessary sync points for this memory in the driver.
DMA_ATTR_NO_KERNEL_MAPPING
--------------------------