[RFC] ARM DMA mapping TODO, v1

Benjamin Herrenschmidt benh at kernel.crashing.org
Wed Apr 27 17:41:07 EDT 2011

> As I said above, I don't think bus code can do it.  Take my example
> above of a tulip pci device on x86 and a tulip pci device on ARM.  Both
> use the same PCI code.
> Maybe something in asm/pci.h - but that invites having lots of bus
> specific header files in asm/.
> A better solution imho would be to have an architecture callback for
> struct device which gets registered, which can inspect the type of
> the device, and set the flag depending on where it appears in the
> tree.

Now -that's gross :-)

For PCI you can have the flag propagate from the PHB down, for busses
without a bus type (platform) then whoever instanciate them (the
platform code) can set that appropriately.


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