lkml.org 
[lkml]   [2009]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH -tip 1/3] IA64: fix swiotlb alloc_coherent for non DMA_64BIT_MASK devices
    > On Thu, 29 Jan 2009 20:41:07 +0900
    > Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
    >
    > > > 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.
    >
    > Hmm, what's 'this initialization'?
    >
    > This patch always sets swiotlb_dma_ops.alloc_coherent to
    > ia64_swiotlb_alloc_coherent.

    I tested your patch, but, ia64_swiotlb_alloc_coherent() was not called with
    CONFIG_GENERIC.

    swiotlb_dma_ops is set by pci_swiotlb_init().
    However, it seems to be not called when CONFIG_IA64_DIG/Generic configuration.


    > > > This patch is sorta updated version of:
    > > >
    > > > http://marc.info/?l=linux-kernel&m=122638215612705&w=2
    > > >

    This old version is effective even CONFIG_GENERIC/CONFIG_IA64_DIG.

    Bye.

    >
    >
    > > 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?


    --
    Yasunori Goto




    \
     
     \ /
      Last update: 2009-01-29 23:57    [W:0.024 / U:30.144 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site