The big picture is that USB drivers can continue to ignore most DMA issues,
though they still must provide DMA-ready buffers (see
-Documentation/PCI/PCI-DMA-mapping.txt). That's how they've worked through
+Documentation/DMA-API-HOWTO.txt). That's how they've worked through
the 2.4 (and earlier) kernels.
OR: they can now be DMA-aware.
force a consistent memory access ordering by using memory barriers. It's
not using a streaming DMA mapping, so it's good for small transfers on
systems where the I/O would otherwise thrash an IOMMU mapping. (See
- Documentation/PCI/PCI-DMA-mapping.txt for definitions of "coherent" and
+ Documentation/DMA-API-HOWTO.txt for definitions of "coherent" and
"streaming" DMA mappings.)
Asking for 1/Nth of a page (as well as asking for N pages) is reasonably
Existing buffers aren't usable for DMA without first being mapped into the
DMA address space of the device. However, most buffers passed to your
driver can safely be used with such DMA mapping. (See the first section
-of Documentation/PCI/PCI-DMA-mapping.txt, titled "What memory is DMA-able?")
+of Documentation/DMA-API-HOWTO.txt, titled "What memory is DMA-able?")
- When you're using scatterlists, you can map everything at once. On some
systems, this kicks in an IOMMU and turns the scatterlists into single
git.openpandora.org / pandora-kernel.git / blobdiff