From dc7d5cf2cab6d1fbb43c5c0569f43b7e4c822760 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Mon, 5 Aug 2013 13:40:47 -0400 Subject: [PATCH] tile PCI RC: add dma_get_required_mask() The standard kernel function dma_get_required_mask() uses the highest DRAM address to determine if 32-bit or 64-bit DMA addressing is needed. This only works on architectures that have direct mapping between the PA and the PCI address space, i.e. those that don't have I/O TLBs or have I/O TLB but choose to use direct mapping. Neither of these are true for tilegx. Whether to use 64-bit DMA should depend on the PCI device's capability only, not on the amount of DRAM installeds, so we now advertise a 64-bit DMA mask unconditionally. Signed-off-by: Chris Metcalf --- arch/tile/include/asm/dma-mapping.h | 4 ++++ arch/tile/kernel/pci-dma.c | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/arch/tile/include/asm/dma-mapping.h b/arch/tile/include/asm/dma-mapping.h index 4a60059876e6..6f522d569132 100644 --- a/arch/tile/include/asm/dma-mapping.h +++ b/arch/tile/include/asm/dma-mapping.h @@ -20,6 +20,10 @@ #include #include +#ifdef __tilegx__ +#define ARCH_HAS_DMA_GET_REQUIRED_MASK +#endif + extern struct dma_map_ops *tile_dma_map_ops; extern struct dma_map_ops *gx_pci_dma_map_ops; extern struct dma_map_ops *gx_legacy_pci_dma_map_ops; diff --git a/arch/tile/kernel/pci-dma.c b/arch/tile/kernel/pci-dma.c index adc369d8c77b..9fef64d70c56 100644 --- a/arch/tile/kernel/pci-dma.c +++ b/arch/tile/kernel/pci-dma.c @@ -607,3 +607,21 @@ int dma_set_coherent_mask(struct device *dev, u64 mask) } EXPORT_SYMBOL(dma_set_coherent_mask); #endif + +#ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK +/* + * The generic dma_get_required_mask() uses the highest physical address + * (max_pfn) to provide the hint to the PCI drivers regarding 32-bit or + * 64-bit DMA configuration. Since TILEGx has I/O TLB/MMU, allowing the + * DMAs to use the full 64-bit PCI address space and not limited by + * the physical memory space, we always let the PCI devices use + * 64-bit DMA if they have that capability, by returning the 64-bit + * DMA mask here. The device driver has the option to use 32-bit DMA if + * the device is not capable of 64-bit DMA. + */ +u64 dma_get_required_mask(struct device *dev) +{ + return DMA_BIT_MASK(64); +} +EXPORT_SYMBOL_GPL(dma_get_required_mask); +#endif -- 2.20.1