From: "wuming" <wuming@ict.ac.cn>
To: <linux-mips@linux-mips.org>
Subject: problem about dma
Date: Mon, 20 Dec 2004 11:46:33 +0800 [thread overview]
Message-ID: <001501c4e646$7f676c00$6f64a8c0@spark> (raw)
In file include/asm-mips/pci.h
there are some functions for dma if the I/O model is non-coherent.
for example:
pci_map_sg
pci_unmap_sg
These two functions exist for ide dma.
Before the dma transfer, pci_map_sg will map the memory space covered by sg_table,
and it will flush and invalidate cache indexed by that memory space.
After the dma transfer, pci_unmap_sg also needs to be called to flush and invalidate
the same cache. But I do not know why the second flush will be demanded.
I think that in the interval between the two flush, there would be nothing to access
the memory covered by the dma. But it is not the case.
I want to know what can access that memory and I need some help.
WARNING: multiple messages have this Message-ID (diff)
From: "wuming" <wuming@ict.ac.cn>
To: linux-mips@linux-mips.org
Subject: problem about dma
Date: Mon, 20 Dec 2004 11:46:33 +0800 [thread overview]
Message-ID: <001501c4e646$7f676c00$6f64a8c0@spark> (raw)
Message-ID: <20041220034633.scqEJU-wjbVFhov5sDIAElhdUUG-YhwlC8YwQQ2i204@z> (raw)
In file include/asm-mips/pci.h
there are some functions for dma if the I/O model is non-coherent.
for example:
pci_map_sg
pci_unmap_sg
These two functions exist for ide dma.
Before the dma transfer, pci_map_sg will map the memory space covered by sg_table,
and it will flush and invalidate cache indexed by that memory space.
After the dma transfer, pci_unmap_sg also needs to be called to flush and invalidate
the same cache. But I do not know why the second flush will be demanded.
I think that in the interval between the two flush, there would be nothing to access
the memory covered by the dma. But it is not the case.
I want to know what can access that memory and I need some help.
next reply other threads:[~2004-12-20 3:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-20 3:46 wuming [this message]
2004-12-20 3:46 ` problem about dma wuming
2004-12-20 8:43 ` Gleb O. Raiko
2004-12-20 9:51 ` wuming
2004-12-20 9:51 ` wuming
2004-12-20 13:14 ` Fuxin Zhang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='001501c4e646$7f676c00$6f64a8c0@spark' \
--to=wuming@ict.ac.cn \
--cc=linux-mips@linux-mips.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox