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author | Olof Johansson <olof@lixom.net> | 2019-12-05 13:16:58 -0800 |
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committer | Olof Johansson <olof@lixom.net> | 2019-12-05 13:18:54 -0800 |
commit | 942e6f8a8314e5550e254519dfba4ccd5170421d (patch) | |
tree | 75ec655b440fbc1c454247af38b5596dd8c78de9 /Documentation/DMA-attributes.txt | |
parent | 336bab731be76a90291697e51d2aed0ad67d7cb5 (diff) | |
parent | b08baef02b26cf7c2123e4a24a2fa1fb7a593ffb (diff) |
Merge mainline/master into arm/fixes
This brings in the mainline tree right after armsoc contents was merged
this release cycle, so that we can re-run savedefconfig, etc.
Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'Documentation/DMA-attributes.txt')
-rw-r--r-- | Documentation/DMA-attributes.txt | 18 |
1 files changed, 0 insertions, 18 deletions
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index 8f8d97f65d73..29dcbe8826e8 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -5,24 +5,6 @@ DMA attributes This document describes the semantics of the DMA attributes that are defined in linux/dma-mapping.h. -DMA_ATTR_WRITE_BARRIER ----------------------- - -DMA_ATTR_WRITE_BARRIER is a (write) barrier attribute for DMA. DMA -to a memory region with the DMA_ATTR_WRITE_BARRIER attribute forces -all pending DMA writes to complete, and thus provides a mechanism to -strictly order DMA from a device across all intervening busses and -bridges. This barrier is not specific to a particular type of -interconnect, it applies to the system as a whole, and so its -implementation must account for the idiosyncrasies of the system all -the way from the DMA device to memory. - -As an example of a situation where DMA_ATTR_WRITE_BARRIER would be -useful, suppose that a device does a DMA write to indicate that data is -ready and available in memory. The DMA of the "completion indication" -could race with data DMA. Mapping the memory used for completion -indications with DMA_ATTR_WRITE_BARRIER would prevent the race. - DMA_ATTR_WEAK_ORDERING ---------------------- |