Re: [Xen-devel] [PATCH v5 11/13] xen: introduce xen_alloc/free_coherent_pages

[Catalin Marinas <catalin.marinas@xxxxxxx>]

On Wed, Sep 11, 2013 at 06:34:17PM +0100, Stefano Stabellini wrote:
> On Wed, 11 Sep 2013, Catalin Marinas wrote:
> >  static inline void set_dma_ops(struct device *dev, struct dma_map_ops *ops)
> >  {
> >     BUG_ON(!dev);
> > @@ -32,7 +39,7 @@ static inline void set_dma_ops(struct device *dev, struct 
> > dma_map_ops *ops)
> >  
> >  static inline int dma_set_mask(struct device *dev, u64 mask)
> >  {
> > -   return get_dma_ops(dev)->set_dma_mask(dev, mask);
> > +   return __get_dma_ops(dev)->set_dma_mask(dev, mask);
> >  }
> >  
> >  #ifdef __arch_page_to_dma
> 
> I don't understand the reason for this change though: shouldn't
> set_dma_mask go via the "default" (whatever that is), like the others?

Under Xen, this would mean xen_dma_ops->set_dma_mask(). I thought you
want to set the default dma address.

I can see why you may want set_dma_mask() for xen_dma_ops but in also
needs to be passed to __get_dma_ops(dev)->set_dma_ops() otherwise the
actual dma_alloc_attrs() will miss the mask (and on arm64 it does
bouncing via swiotlb).

-- 
Catalin

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