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| author | Jens Axboe <axboe@kernel.dk> | 2012-05-01 16:29:55 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-05-01 16:29:55 +0400 |
| commit | 0b7877d4eea3f93e3dd941999522bbd8c538cb53 (patch) | |
| tree | ade6d4e411b9b9b569c802e3b2179826162c934c /Documentation/DMA-attributes.txt | |
| parent | bd1a68b59c8e3bce45fb76632c64e1e063c3962d (diff) | |
| parent | 69964ea4c7b68c9399f7977aa5b9aa6539a6a98a (diff) | |
| download | linux-0b7877d4eea3f93e3dd941999522bbd8c538cb53.tar.xz | |
Merge tag 'v3.4-rc5' into for-3.5/core
The core branch is behind driver commits that we want to build
on for 3.5, hence I'm pulling in a later -rc.
Linux 3.4-rc5
Conflicts:
Documentation/feature-removal-schedule.txt
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'Documentation/DMA-attributes.txt')
| -rw-r--r-- | Documentation/DMA-attributes.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index b768cc0e402b..5c72eed89563 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -31,3 +31,21 @@ may be weakly ordered, that is that reads and writes may pass each other. Since it is optional for platforms to implement DMA_ATTR_WEAK_ORDERING, those that do not will simply ignore the attribute and exhibit default behavior. + +DMA_ATTR_WRITE_COMBINE +---------------------- + +DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be +buffered to improve performance. + +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. |