Messages in this thread | | | Date | Thu, 29 Jan 2009 20:41:07 +0900 | From | Yasunori Goto <> | Subject | Re: [PATCH -tip 1/3] IA64: fix swiotlb alloc_coherent for non DMA_64BIT_MASK devices |
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> Before the dma ops unification, IA64 always uses GFP_DMA for > dma_alloc_coherent like: > > #define dma_alloc_coherent(dev, size, handle, gfp) \ > platform_dma_alloc_coherent(dev, size, handle, (gfp) | GFP_DMA) > > This GFP_DMA enforcement doesn't make sense for IOMMUs since they can > do address translation to give addresses that devices can access > to. The IOMMU drivers ignore the zone flag. However, this is still > necessary for swiotlb since it can't do address translation. > > We don't always need to use GFP_DMA for swiotlb. We need GFP_DMA for > devices incapable of 64bit DMA. > > This patch is sorta updated version of: > > http://marc.info/?l=linux-kernel&m=122638215612705&w=2 > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> > Cc: Yasunori Goto <y-goto@jp.fujitsu.com> > --- > arch/ia64/kernel/pci-swiotlb.c | 10 +++++++++- > 1 files changed, 9 insertions(+), 1 deletions(-) > > diff --git a/arch/ia64/kernel/pci-swiotlb.c b/arch/ia64/kernel/pci-swiotlb.c > index 717ad4f..573f02c 100644 > --- a/arch/ia64/kernel/pci-swiotlb.c > +++ b/arch/ia64/kernel/pci-swiotlb.c > @@ -13,8 +13,16 @@ > int swiotlb __read_mostly; > EXPORT_SYMBOL(swiotlb); > > +static void *ia64_swiotlb_alloc_coherent(struct device *dev, size_t size, > + dma_addr_t *dma_handle, gfp_t gfp) > +{ > + if (dev->coherent_dma_mask != DMA_64BIT_MASK) > + gfp |= GFP_DMA; > + return swiotlb_alloc_coherent(dev, size, dma_handle, gfp); > +} > + > struct dma_map_ops swiotlb_dma_ops = { > - .alloc_coherent = swiotlb_alloc_coherent, > + .alloc_coherent = ia64_swiotlb_alloc_coherent, > .free_coherent = swiotlb_free_coherent, > .map_page = swiotlb_map_page, > .unmap_page = swiotlb_unmap_page, > -- > 1.6.0.6
Though I may be misunderstanding something, this initialization seems to be called only when CONFIG_IA64_DIG_VTD is on.
CONFIG_IA64_DIG_VTD platform_dma_init() -> pci_iommu_alloc() -> pci_swiotlb_init()
CONFIG_IA64_DIG/CONFIG_IA64_GENERIC platform_dma_init() -> swiotlb_dma_init()
Is it intended? Do you wish GFP_DMA should be always ON when generic config?
Bye.
-- Yasunori Goto
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