All of lore.kernel.org
 help / color / mirror / Atom feed
From: William Jhun <wjhun@ayrnetworks.com>
To: linux-kernel@vger.kernel.org
Subject: Possible discrepancy regarding streaming DMA mappings in DMA-mapping.txt?
Date: Thu, 23 May 2002 16:24:25 -0700	[thread overview]
Message-ID: <20020523162425.G7205@ayrnetworks.com> (raw)

In the explanation of streaming DMA mappings and holding onto a mapping
for multiple DMA operations, the file Documentation/DMA-mapping.txt
(line 507) says the following:

	If you need to use the same streaming DMA region multiple times
	and touch the data in between the DMA transfers, just map it
	with pci_map_{single,sg}, and after each DMA transfer call
	either:

		pci_dma_sync_single(dev, dma_handle, size, direction);

	or:

		pci_dma_sync_sg(dev, sglist, nents, direction);

	as appropriate.

However, shouldn't pci_dma_sync_*() be called *before* each
PCI_DMA_TODEVICE DMA transfer (after the CPU write, of course) and
*after* each PCI_DMA_FROMDEVICE DMA transfer (before CPU access)? And,
of course, before and after a "bidirectional" DMA, if appropriate.

Thanks,
William

             reply	other threads:[~2002-05-23 23:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-05-23 23:24 William Jhun [this message]
2002-05-24  5:59 ` Possible discrepancy regarding streaming DMA mappings in DMA-mapping.txt? David S. Miller
2002-05-24 17:43   ` William Jhun
2002-05-24 17:42     ` David S. Miller
2002-05-24 20:37       ` William Jhun
2002-05-24 20:26         ` David S. Miller
2002-05-24 20:58           ` William Jhun
2002-05-24 20:53             ` David S. Miller
2002-05-24 21:18               ` William Jhun
2002-05-25  3:41       ` [PATCH] Functions to complement pci_dma_sync_{single,sg}(). (was: Re: Possible discrepancy regarding streaming DMA mappings in DMA-mapping.txt?) William Jhun
2002-05-25 23:04         ` [PATCH] Functions to complement pci_dma_sync_{single,sg}() David S. Miller
2002-05-26  7:09           ` [PATCH] DMA-mapping.txt (was Re: [PATCH] Functions to complement pci_dma_sync_{single,sg}().) William Jhun

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=20020523162425.G7205@ayrnetworks.com \
    --to=wjhun@ayrnetworks.com \
    --cc=linux-kernel@vger.kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.