hi stefan: Thanks for your reply. 2011/10/30, Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>: > On Oct 30 yoma sophian wrote: >> in scsi_init_sgtable, we create sgtable, sdb->table.sgl, and get the >> page from blk_rq_map_sg. >> But when the dma_address of sdb->table.sgl will be calclated out >> before send the scsi command down to the lower level driver? > > The low level driver, not SCSI core, is responsible to obtain a DMA > address. Why I ask this because I found there is no same transformation for scsi usb subsystem. Would anyone can let me know where it is? > > dma_map_sg() maps the scatter-gather list into DMA memory. Then you can > iterate over the list with for_each_sg and obtain DMA handles and lengths > with sg_dma_address() and sg_dma_len(). E.g.: > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/firewire/sbp2.c;h=41841a3e3f99c9acd4c4fc72c972626d8dffdcee;hb=02f8c6aee8df3cdc935e9bdd4f2d020306035dbe#l1398 > -- > Stefan Richter > -=====-==-== =-=- ====- > http://arcgraph.de/sr/ > Retards, -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
