Re: [Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces.

Grant Grundler
2003-05-16T17:59:24Z

On Fri, May 16, 2003 at 12:36:15PM -0500, James Bottomley wrote:
> You mean we need an interface that is called when the CPU hands off the
> region to the device and again when the CPU reclaims it (so we always
> get the writeback or invalidate in the correct place).

yes

> How about just adding an ownership attribute to dma_sync..? It would
> either be DMA_OWNER_CPU or DMA_OWNER_DEVICE?

I prefer davem's suggestion of a different function call (*_to_cpu and
*_to_dev) rather than making the same function do completely different
things based on parameters. Keeps API documentation and resulting
implementations for each smaller.

> Of course, retrofitting something like this is going to be fun.

It's not so bad.
It's really only needed for non-coherent machines.
Folks who care about those platforms probably already know where
those calls belong.

grant