Re: DMA API issues

[Jamey Hicks]

James Bottomley wrote:

> On Fri, 2004-06-18 at 19:14, Ian Molton wrote:
>  
>
> > On 18 Jun 2004 19:04:11 -0500
> > James Bottomley <James.Bottomley@xxxxxxxxxxxx> wrote:
> >
> >    
> >
> > > Because the piece of memory you wish to access is bus remote. 
> > >      
> > No, its *not*
> >
> > my CPU can write there directly.
> >
> > no strings attached.
> >
> > the DMA API just only understands how to map from RAM, not anything
> > else.
> >    
>
> I think you'll actually find that it is.  OHCI is a device (representing
> a USB hub), it's attached to the system by some interface that
> constitutes a bus (the bus interface transforming the CPU access cycles
> to device access cycles, translating interrupts etc.).
>
>  
Bus remote is a red herring in this case.  The only difference between 
this case and the ones supported by the coherent_dma_mask is that the 
constraint on placement of the allocated memory cannot be encoded as a 
bitmask.

Jamey

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