--- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -375,7 +375,6 @@ config ARCH_IXP4XX select GENERIC_GPIO select GENERIC_TIME select GENERIC_CLOCKEVENTS - select DMABOUNCE if PCI help Support for Intel's IXP4XX (XScale) family of processors. --- a/arch/arm/mach-ixp4xx/Kconfig +++ b/arch/arm/mach-ixp4xx/Kconfig @@ -193,6 +193,45 @@ config IXP4XX_INDIRECT_PCI need to use the indirect method instead. If you don't know what you need, leave this option unselected. +config IXP4XX_LEGACY_DMABOUNCE + bool "legacy PCI DMA bounce support" + depends on PCI + default n + select DMABOUNCE + help + The IXP4xx is limited to a 64MB window for PCI DMA, which + requires that PCI accesses above 64MB are bounced via buffers + below 64MB. Furthermore the IXP4xx has an erratum where PCI + read prefetches just below the 64MB limit can trigger lockups. + + The kernel has traditionally handled these two issue by using + ARM specific DMA bounce support code for all accesses >= 64MB. + That code causes problems of its own, so it is desirable to + disable it. As the kernel now has a workaround for the PCI read + prefetch erratum, it no longer requires the ARM bounce code. + + Enabling this option makes IXP4xx continue to use the problematic + ARM DMA bounce code. Disabling this option makes IXP4xx use the + kernel's generic bounce code. + + Say 'N'. + +config IXP4XX_ZONE_DMA + bool "Support > 64MB RAM" + depends on !IXP4XX_LEGACY_DMABOUNCE + default y + select ZONE_DMA + help + The IXP4xx is limited to a 64MB window for PCI DMA, which + requires that PCI accesses above 64MB are bounced via buffers + below 64MB. + + Disabling this option allows you to omit the support code for + DMA-able memory allocations and DMA bouncing, but the kernel + will then not work properly if more than 64MB of RAM is present. + + Say 'Y' unless your platform is limited to <= 64MB of RAM. + config IXP4XX_QMGR tristate "IXP4xx Queue Manager support" help --- a/arch/arm/mach-ixp4xx/common-pci.c +++ b/arch/arm/mach-ixp4xx/common-pci.c @@ -321,27 +321,38 @@ static int abort_handler(unsigned long a */ static int ixp4xx_pci_platform_notify(struct device *dev) { - if(dev->bus == &pci_bus_type) { - *dev->dma_mask = SZ_64M - 1; + if (dev->bus == &pci_bus_type) { + *dev->dma_mask = SZ_64M - 1; dev->coherent_dma_mask = SZ_64M - 1; +#ifdef CONFIG_DMABOUNCE dmabounce_register_dev(dev, 2048, 4096); +#endif } return 0; } static int ixp4xx_pci_platform_notify_remove(struct device *dev) { - if(dev->bus == &pci_bus_type) { +#ifdef CONFIG_DMABOUNCE + if (dev->bus == &pci_bus_type) dmabounce_unregister_dev(dev); - } +#endif return 0; } +#ifdef CONFIG_DMABOUNCE int dma_needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size) { + /* Note that this returns true for the last page below 64M due to + * IXP4xx erratum 15 (SCR 1289), which states that PCI prefetches + * can cross the boundary between valid memory and a reserved region + * causing AHB bus errors and a lock-up. + */ return (dev->bus == &pci_bus_type ) && ((dma_addr + size) >= SZ_64M); } +#endif +#ifdef CONFIG_ZONE_DMA /* * Only first 64MB of memory can be accessed via PCI. * We use GFP_DMA to allocate safe buffers to do map/unmap. @@ -364,6 +375,7 @@ void __init ixp4xx_adjust_zones(int node zhole_size[1] = zhole_size[0]; zhole_size[0] = 0; } +#endif void __init ixp4xx_pci_preinit(void) { @@ -517,19 +529,35 @@ struct pci_bus * __devinit ixp4xx_scan_b int pci_set_dma_mask(struct pci_dev *dev, u64 mask) { - if (mask >= SZ_64M - 1 ) +#ifdef CONFIG_DMABOUNCE + if (mask >= SZ_64M - 1) return 0; return -EIO; +#else + /* Only honour masks < SZ_64M. Silently ignore masks >= SZ_64M + as generic drivers do not know about IXP4xx PCI DMA quirks. */ + if (mask < SZ_64M) + dev->dma_mask = mask; + return 0; +#endif } int pci_set_consistent_dma_mask(struct pci_dev *dev, u64 mask) { - if (mask >= SZ_64M - 1 ) +#ifdef CONFIG_DMABOUNCE + if (mask >= SZ_64M - 1) return 0; return -EIO; +#else + /* Only honour masks < SZ_64M. Silently ignore masks >= SZ_64M + as generic drivers do not know about IXP4xx PCI DMA quirks. */ + if (mask < SZ_64M) + dev->dev.coherent_dma_mask = mask; + return 0; +#endif } EXPORT_SYMBOL(ixp4xx_pci_read); --- a/arch/arm/mach-ixp4xx/include/mach/memory.h +++ b/arch/arm/mach-ixp4xx/include/mach/memory.h @@ -16,10 +16,12 @@ #if !defined(__ASSEMBLY__) && defined(CONFIG_PCI) +#ifdef CONFIG_ZONE_DMA void ixp4xx_adjust_zones(int node, unsigned long *size, unsigned long *holes); #define arch_adjust_zones(node, size, holes) \ ixp4xx_adjust_zones(node, size, holes) +#endif #define ISA_DMA_THRESHOLD (SZ_64M - 1) #define MAX_DMA_ADDRESS (PAGE_OFFSET + SZ_64M)