Re: [PATCH V2 2/3] powerpc: Add support for swiotlb on 32-bit

[Becky Bruce]

On May 22, 2009, at 5:51 AM, FUJITA Tomonori wrote:

> On Thu, 21 May 2009 13:18:54 -0700
> Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>
> > Becky Bruce wrote:
> > > I can work with that, but it's going to be a bit inefficient, as I
> > > actually need the dma_addr_t, not the phys_addr_t, so I'll have to
> > > convert.  In every case, this is a conversion I've already done and
> > > that I need in the calling code as well.  Can we pass in both the
> > > phys_addr_t and the dma_addr_t?
> >
> > The Xen implementation would needs to do the phys to bus conversion  
> > page
> > by page anyway, so it wouldn't help much.  But it also wouldn't hurt.
> >
> > How expensive is the phys-to-bus conversion on power?  Is it worth
> > making the interface more complex for?  Would passing phys+bus mean  
> > that
> > we wouldn't also need to pass dev?
>
> I don't think so. POWERPC needs it.

Hrm, it looks like my response to this got dropped.  Fujita is correct  
- we still need the dev on powerpc because we use it to get device- 
specific information that is used to determining when we need to  
actually bounce.

Cheers,
B

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