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authorChris Metcalf <cmetcalf@tilera.com>2013-08-05 13:40:47 -0400
committerChris Metcalf <cmetcalf@tilera.com>2013-08-06 12:56:00 -0400
commitdc7d5cf2cab6d1fbb43c5c0569f43b7e4c822760 (patch)
tree1260be5d29786ad3ac5e515d2033095721a31c9b /arch/tile/kernel
parent8d9e53b93de7383d5bb4b3507f146bfcd83c6e5d (diff)
downloadop-kernel-dev-dc7d5cf2cab6d1fbb43c5c0569f43b7e4c822760.zip
op-kernel-dev-dc7d5cf2cab6d1fbb43c5c0569f43b7e4c822760.tar.gz
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 <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/kernel')
-rw-r--r--arch/tile/kernel/pci-dma.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/tile/kernel/pci-dma.c b/arch/tile/kernel/pci-dma.c
index adc369d..9fef64d 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
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