The patch titled DMA-API.txt: fix description of pci_map_sg/dma_map_sg scatterlists handling has been added to the -mm tree. Its filename is dma-apitxt-fix-description-of-pci_map_sg-dma_map_sg-scatterlists-handling.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: DMA-API.txt: fix description of pci_map_sg/dma_map_sg scatterlists handling From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> - pci_map_sg/dma_map_sg are used with a scatter gather list that doesn't come from the block layer (e.g. some network drivers do). - how IOMMUs merge adjacent elements of the scatter/gather list is independent of how the block layer determines sees elements. Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Cc: Tejun Heo <htejun@xxxxxxxxx> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/DMA-API.txt | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff -puN Documentation/DMA-API.txt~dma-apitxt-fix-description-of-pci_map_sg-dma_map_sg-scatterlists-handling Documentation/DMA-API.txt --- a/Documentation/DMA-API.txt~dma-apitxt-fix-description-of-pci_map_sg-dma_map_sg-scatterlists-handling +++ a/Documentation/DMA-API.txt @@ -316,12 +316,10 @@ reduce current DMA mapping usage or dela 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. _ Patches currently in -mm which might be from fujita.tomonori@xxxxxxxxxxxxx are origin.patch linux-next.patch dma-apitxt-fix-description-of-pci_map_sg-dma_map_sg-scatterlists-handling.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html