From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: yoma sophian <sophian.yoma@gmail.com>
Cc: linux-scsi@vger.kernel.org
Subject: Re: question about passing physical address to lower level driver in scsi
Date: Sun, 30 Oct 2011 13:28:21 +0100 [thread overview]
Message-ID: <20111030132821.4df33f1e@stein> (raw)
In-Reply-To: <CADUS3okkKEu_Re1FU_AvVk6agFwrmx0mwzbMSmso6pV8HFfWMA@mail.gmail.com>
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.
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/
next prev parent reply other threads:[~2011-10-30 12:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-30 12:05 question about passing physical address to lower level driver in scsi yoma sophian
2011-10-30 12:28 ` Stefan Richter [this message]
2011-10-31 1:53 ` yoma sophian
2011-10-31 6:11 ` Julian Calaby
2011-10-31 12:22 ` Stefan Richter
2011-10-31 12:28 ` yoma sophian
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