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    SubjectRe: ARM: 2.6.3[45] PCI regression (IXP4xx and PXA?)
    On Sun, Aug 15, 2010 at 02:42:51PM +0900, FUJITA Tomonori wrote:
    > On Sat, 14 Aug 2010 19:46:05 +0100
    > Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
    >
    > > On Sat, Aug 14, 2010 at 06:30:37PM +0900, FUJITA Tomonori wrote:
    > > > On Fri, 13 Aug 2010 22:54:13 +0100
    > > > Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
    > > > > This means that when dmabounce comes to allocate the replacement
    > > > > buffer, it gets a buffer which won't be accessible to the DMA
    > > > > controller
    > > >
    > > > Really? looks like dmabounce does nothing for coherent memory that
    > > > dma_alloc_coherent() allocates.
    > > >
    > > > The following very hacky patch works?
    > >
    > > So what happens if you use a driver which uses dma_alloc_coherent()
    > > directly? Should the driver really be passed memory which is
    > > inaccessible to the device because its outside the host bridge PCI
    > > window?
    >
    > I'm not sure what you mean.
    >
    > A driver which uses dma_alloc_coherent() directly should
    > work. dma_alloc_coherent() allocates memory with GFP_DMA with that
    > patch for dmabounce devices. So the driver gets the access-able
    > memory.
    >
    > The memory that dma_alloc_coherent() returns should be always
    > consistent. We can't bounce it. All we can do is returning a memory
    > that a device (and its bus) can access to.
    >
    > Krzysztof, can you try the patch?

    Why bother when we both agree that the patch is a dirty hack?

    Come up with something cleaner first.


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