diff options
| -rw-r--r-- | Documentation/DMA-API.txt | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index b8e86460046e..b462bb149543 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -316,12 +316,10 @@ 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. |