Re: [Xen-devel] [PATCH v6 15/19] swiotlb-xen: call dma_capable only if dev->dma_mask is allocated

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

The real issue is that some devices (xgmac, I am looking at you), don't
set the dma_mask, even though they are perfectly capable of doing dma.

Maybe I should modify the arm implementation of dma_capable (see
http://marc.info/?l=linux-kernel&m=138029832007821&w=2) to ignore the
dma_mask.

On Mon, 30 Sep 2013, Konrad Rzeszutek Wilk wrote:
> On Fri, Sep 27, 2013 at 05:10:03PM +0100, Stefano Stabellini wrote:
> 
> Why? I am looking at X86 and IA64 and I see:
> 
>  79         if (!dev->dma_mask)                                               
>       
>  80                 return 0;           
> 
> 
> Why not port dma_capable over to ARM?
> 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > ---
> >  drivers/xen/swiotlb-xen.c |    6 +++---
> >  1 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 790c2eb..3011736 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -512,7 +512,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, 
> > struct page *page,
> >      * buffering it.
> >      */
> >     if (!xen_feature(XENFEAT_auto_translated_physmap) &&
> > -       dma_capable(dev, dev_addr, size) &&
> > +       dev->dma_mask && dma_capable(dev, dev_addr, size) &&
> >         !range_straddles_page_boundary(phys, size) && !swiotlb_force)
> >             return dev_addr;
> >  
> > @@ -532,7 +532,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, 
> > struct page *page,
> >     /*
> >      * Ensure that the address returned is DMA'ble
> >      */
> > -   if (!dma_capable(dev, dev_addr, size)) {
> > +   if (dev->dma_mask && !dma_capable(dev, dev_addr, size)) {
> >             swiotlb_tbl_unmap_single(dev, map, size, dir);
> >             dev_addr = 0;
> >     }
> > @@ -660,7 +660,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct 
> > scatterlist *sgl,
> >  
> >             if (swiotlb_force ||
> >                 xen_feature(XENFEAT_auto_translated_physmap) ||
> > -               !dma_capable(hwdev, dev_addr, sg->length) ||
> > +               (hwdev->dma_mask && !dma_capable(hwdev, dev_addr, 
> > sg->length)) ||
> >                 range_straddles_page_boundary(paddr, sg->length)) {
> >                     /*
> >                      * Pass the dma_addr of the first slab in the iotlb 
> > buffer as
> > -- 
> > 1.7.2.5
> > 
> 

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