diff options
| author | merge <null@invalid> | 2009-01-22 13:55:32 +0000 |
|---|---|---|
| committer | Andy Green <agreen@octopus.localdomain> | 2009-01-22 13:55:32 +0000 |
| commit | aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 (patch) | |
| tree | fbb786d0ac6f8a774fd834e9ce951197e60fbffa /Documentation/DMA-API.txt | |
| parent | f2d78193eae5dccd3d588d2c8ea0866efc368332 (diff) | |
MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141
pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040
stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch
mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage:
From: Andy Green <andy@openmoko.com>
fix-stray-endmenu.patch
Signed-off-by: Andy Green <andy@openmoko.com>
Diffstat (limited to 'Documentation/DMA-API.txt')
| -rw-r--r-- | Documentation/DMA-API.txt | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index b8e86460046..52441694fe0 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -170,16 +170,15 @@ Returns: 0 if successful and a negative error if not. u64 dma_get_required_mask(struct device *dev) -After setting the mask with dma_set_mask(), this API returns the -actual mask (within that already set) that the platform actually -requires to operate efficiently. Usually this means the returned mask +This API returns the mask that the platform requires to +operate efficiently. Usually this means the returned mask is the minimum required to cover all of memory. Examining the required mask gives drivers with variable descriptor sizes the opportunity to use smaller descriptors as necessary. Requesting the required mask does not alter the current mask. If you -wish to take advantage of it, you should issue another dma_set_mask() -call to lower the mask again. +wish to take advantage of it, you should issue a dma_set_mask() +call to set the mask to the value returned. Part Id - Streaming DMA mappings @@ -316,12 +315,10 @@ reduce current DMA mapping usage or delay and try again later). pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg, int nents, int direction) -Maps a scatter gather list from the block layer. - Returns: the number of physical segments mapped (this may be shorter -than <nents> passed in if the block layer determines that some -elements of the scatter/gather list are physically adjacent and thus -may be mapped with a single entry). +than <nents> passed in if some elements of the scatter/gather list are +physically or virtually adjacent and an IOMMU maps them with a single +entry). Please note that the sg cannot be mapped again if it has been mapped once. The mapping process is allowed to destroy information in the sg. |