From: David Brownell Date: Sat, 1 Apr 2006 18:21:52 +0000 (-0800) Subject: [PATCH] dma doc updates X-Git-Tag: v2.6.17-rc2~32^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=21440d313358043b0ce5e43b00ff3c9b35a8616c;p=pandora-kernel.git [PATCH] dma doc updates This updates the DMA API documentation to address a few issues: - The dma_map_sg() call results are used like pci_map_sg() results: using sg_dma_address() and sg_dma_len(). That's not wholly obvious to folk reading _only_ the "new" DMA-API.txt writeup. - Buffers allocated by dma_alloc_coherent() may not be completely free of coherency concerns ... some CPUs also have write buffers that may need to be flushed. - Cacheline coherence issues are now mentioned as being among issues which affect dma buffers, and complicate/prevent using of static and (especially) stack based buffers with the DMA calls. I don't think many drivers currently need to worry about flushing write buffers, but I did hit it with one SOC using external SDRAM for DMA descriptors: without explicit writebuffer flushing, the on-chip DMA controller accessed descriptors before the CPU completed the writes. Signed-off-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed