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SubjectRe: Suggestions for how to remove bus_to_virt()
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 > > A cleaner solution would be to make the dma_ API really use the device
> > it's passed anyway, and allow drivers to override the standard PCI
> > stuff nicely. But that would be major surgery, I guess.

> Clean but expensive, you should not force the rest of the kernel
> to eat the cost of something you want to do when it's totally
> unnecessary for most other users.

OK, fair enough.

> For example, x86 never needs to do anything other than a direct
> virt_to_phys translation to produce a DMA address, no matter what
> bus the device is on. It's a single simple integer adjustment
> that can be done inline in about 2 or 3 instructions at most.

<pedantic>Except x86 needs to handle systems with IOMMUs now...</pedantic>

> If you need device level DMA mapping semantics, create them for your
> device type. This is what USB does, btw.

Makes sense -- Ralph, I would suggest looking at USB as a model.

- R.
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