Re: [RFC] generic device DMA implementation

From: David Gibson (
Date: Sun Dec 08 2002 - 00:28:43 EST

On Sat, Dec 07, 2002 at 11:26:57AM +0000, Russell King wrote:
> On Sat, Dec 07, 2002 at 08:45:30PM +1100, David Gibson wrote:
> > Actually, no, since my idea was to remove the "consistent_alloc()"
> > path from the driver entirely - leaving only the map/sync approach.
> > That gives a result which is correct everywhere (afaict) but (as
> > you've since pointed out) will perform poorly on platforms where the
> > map/sync operations are expensive.
> As I've also pointed out in the past couple of days, doing this will
> mean that you then need to teach the drivers to align structures to
> cache line boundaries. Otherwise, you _will_ get into a situation
> where you _will_ loose data.

Sure, but that's already an issue with the current streaming DMA API.

David Gibson			| For every complex problem there is a	| solution which is simple, neat and
				| wrong.
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