Messages in this thread | | | Date | Fri, 13 Aug 2010 15:23:53 +0900 | Subject | Re: ARM: 2.6.3[45] PCI regression (IXP4xx and PXA?) | From | FUJITA Tomonori <> |
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On Wed, 11 Aug 2010 08:25:32 +0100 Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> On Wed, Aug 11, 2010 at 11:06:00AM +0900, FUJITA Tomonori wrote: > > On Tue, 10 Aug 2010 22:36:21 +0200 > > Krzysztof Halasa <khc@pm.waw.pl> wrote: > > > > > 6fee48cd330c68332f9712bc968d934a1a84a32a broke > > > pci_set_consistent_dma_mask() on IXP4xx and most probably PXA. Affected > > > devices are e.g. IDE controller (CS5536-based: disk inaccessible) and > > > e1000 ethernet ("Detected Tx Unit Hang"). > > > > Sorry about that. > > > > > The attached patch makes it work again, though I'm not sure it's the > > > best solution. > > > > I think that we should avoid adding "#ifdef CONFIG_DMABOUNCE" to a > > generic place. > > > > Why the above patch breaks dmabounce.c? We can't set dev->coherent_dma_mask? > > It doesn't break dmabounce. > > What it breaks is the fact that a PCI device which can do 32-bit DMA is > connected to a PCI bus which can only access the first 64MB of memory > through the host bridge, but the system has more than 64MB available. > > Allowing a 32-bit DMA mask means that dmabounce can't detect that memory > above 64MB needs to be bounced to memory below the 64MB boundary.
But dmabounce doesn't look at dev->coherent_dma_mask.
The change breaks __dma_alloc_buffer()? If we set dev->coherent_dma_mask to DMA_BIT_MASK(32) for ixp4xx's pci devices, __dma_alloc_buffer() doesn't use GFP_DMA.
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