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SubjectRE: DMA and Cache coherency on machines without hardware enforced
Date
Pete Zaitcev [mailto:zaitcev@metabyte.com] wrote:
> Also note that if one wants to produce the bus address to
> program a DMA master he/she must use virt_to_bus(page), and NOT
> virt_to_bus(ptr).

Where did you get this requirement from? That isn't what
Documentation/IO-mapping.txt appears to indicate.

It gives a prototype of
bus_addr = virt_to_bus(virt_addr);
and even the examples don't seem to indicate that it is anything other than
an address that is passed in.

When you say you must use virt_to_bus(page), I'm guessing you mean that the
address must be page aligned.

-Bret

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