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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

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