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Documentation: fix block/biodoc.txt dma mapping description 

- It looks incorrect to use blk_rq_map_sg with pci_map_page here about
  DMA mappings. dma_map_sg?

- better to use dma_map_page instead of pci_map_page.
  http://marc.info/?l=linux-kernel&m=126596737604808&w=2

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
FUJITA Tomonori 2010-03-08 09:11:07 +01:00 committed by Jens Axboe
parent 8bf8c376ab
commit c2282adbde
1 changed files with 2 additions and 2 deletions
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Documentation/block/biodoc.txt
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@ -1162,8 +1162,8 @@ where a driver received a request ala this before:
As mentioned, there is no virtual mapping of a bio. For DMA, this is
not a problem as the driver probably never will need a virtual mapping.
Instead it needs a bus mapping (pci_map_page for a single segment or
use blk_rq_map_sg for scatter gather) to be able to ship it to the driver. For
Instead it needs a bus mapping (dma_map_page for a single segment or
use dma_map_sg for scatter gather) to be able to ship it to the driver. For
PIO drivers (or drivers that need to revert to PIO transfer once in a
while (IDE for example)), where the CPU is doing the actual data
transfer a virtual mapping is needed. If the driver supports highmem I/O,