ARM: 2.6.3[45] PCI regression (IXP4xx and PXA?)
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From: Krzysztof Halasa on 10 Aug 2010 16:40 Hi, Noticed this problem a bit late :-( 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"). The attached patch makes it work again, though I'm not sure it's the best solution. Ideas? Signed-off-by: Krzysztof Hałasa <khc(a)pm.waw.pl> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index ca32ed7..bd2a7d3 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -129,6 +129,14 @@ static inline u64 dma_get_mask(struct device *dev) static inline int dma_set_coherent_mask(struct device *dev, u64 mask) { +#ifdef CONFIG_DMABOUNCE + if (dev->archdata.dmabounce) { + if (mask >= ISA_DMA_THRESHOLD) + return 0; + else + return -EIO; + } +#endif if (!dma_supported(dev, mask)) return -EIO; dev->coherent_dma_mask = mask; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: FUJITA Tomonori on 10 Aug 2010 22:10 On Tue, 10 Aug 2010 22:36:21 +0200 Krzysztof Halasa <khc(a)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? > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index ca32ed7..bd2a7d3 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -129,6 +129,14 @@ static inline u64 dma_get_mask(struct device *dev) > > static inline int dma_set_coherent_mask(struct device *dev, u64 mask) > { > +#ifdef CONFIG_DMABOUNCE > + if (dev->archdata.dmabounce) { > + if (mask >= ISA_DMA_THRESHOLD) > + return 0; > + else > + return -EIO; > + } > +#endif > if (!dma_supported(dev, mask)) > return -EIO; > dev->coherent_dma_mask = mask; > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo(a)vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Russell King - ARM Linux on 11 Aug 2010 03:30 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(a)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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: FUJITA Tomonori on 13 Aug 2010 02:30 On Wed, 11 Aug 2010 08:25:32 +0100 Russell King - ARM Linux <linux(a)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(a)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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Russell King - ARM Linux on 13 Aug 2010 18:00
On Fri, Aug 13, 2010 at 03:23:53PM +0900, FUJITA Tomonori wrote: > On Wed, 11 Aug 2010 08:25:32 +0100 > Russell King - ARM Linux <linux(a)arm.linux.org.uk> wrote: > > 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. With an incorrect coherent_dma_mask, dma_alloc_coherent() will return memory outside of the 64MB window. This means that when dmabounce comes to allocate the replacement buffer, it gets a buffer which won't be accessible to the DMA controller - which is a condition it doesn't check for. Ergo, it breaks dmabounce. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |