Re: [PATCH 1/3] swiotlb: Export maximum allocation size

[Konrad Rzeszutek Wilk]

On Fri, Jan 11, 2019 at 10:12:31AM +0100, Joerg Roedel wrote:
> On Thu, Jan 10, 2019 at 12:02:05PM -0500, Konrad Rzeszutek Wilk wrote:
> > Why not use swiotlb_nr_tbl ? That is how drivers/gpu/drm use to figure if they
> > need to limit the size of pages.
> 
> That function just exports the overall size of the swiotlb aperture, no?
> What I need here is the maximum size for a single mapping.

Yes. The other drivers just assumed that if there is SWIOTLB they would use
the smaller size by default (as in they knew the limitation).

But I agree it would be better to have something smarter - and also convert the
DRM drivers to piggy back on this.

Or alternatively we could make SWIOTLB handle bigger sizes..
> 
> Regards,
> 
> 	Joerg