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Date: Thu, 23 May 2002 16:24:25 -0700
From: William Jhun <wjhun@ayrnetworks.com>
To: linux-kernel@vger.kernel.org
Subject: Possible discrepancy regarding streaming DMA mappings in DMA-mapping.txt?
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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