Re: [RFC] generic device DMA implementation

[David Gibson <david@gibson.dropbear.id.au>]

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
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson