diff options
author | Glauber Costa <gcosta@redhat.com> | 2008-04-08 13:20:55 -0300 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-04-19 19:19:57 +0200 |
commit | 8e0c379718ef32967deea55937895bfc9b493dd8 (patch) | |
tree | 4176210a3359f4d7421a8b7e0cec29e848e8d68a /arch/x86/kernel/pci-dma.c | |
parent | bca5c09663030bdd18ab1b3ccb6671f663c3345a (diff) |
x86: merge dma_supported
The code for both arches are very similar, so this patch merge them.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/pci-dma.c')
-rw-r--r-- | arch/x86/kernel/pci-dma.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 48cccbe51aa..7d3bd652c36 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -14,6 +14,8 @@ EXPORT_SYMBOL(forbid_dac); const struct dma_mapping_ops *dma_ops; EXPORT_SYMBOL(dma_ops); +int iommu_sac_force __read_mostly = 0; + #ifdef CONFIG_IOMMU_DEBUG int panic_on_overflow __read_mostly = 1; int force_iommu __read_mostly = 1; @@ -103,6 +105,48 @@ void __init pci_iommu_alloc(void) } #endif +int dma_supported(struct device *dev, u64 mask) +{ +#ifdef CONFIG_PCI + if (mask > 0xffffffff && forbid_dac > 0) { + printk(KERN_INFO "PCI: Disallowing DAC for device %s\n", + dev->bus_id); + return 0; + } +#endif + + if (dma_ops->dma_supported) + return dma_ops->dma_supported(dev, mask); + + /* Copied from i386. Doesn't make much sense, because it will + only work for pci_alloc_coherent. + The caller just has to use GFP_DMA in this case. */ + if (mask < DMA_24BIT_MASK) + return 0; + + /* Tell the device to use SAC when IOMMU force is on. This + allows the driver to use cheaper accesses in some cases. + + Problem with this is that if we overflow the IOMMU area and + return DAC as fallback address the device may not handle it + correctly. + + As a special case some controllers have a 39bit address + mode that is as efficient as 32bit (aic79xx). Don't force + SAC for these. Assume all masks <= 40 bits are of this + type. Normally this doesn't make any difference, but gives + more gentle handling of IOMMU overflow. */ + if (iommu_sac_force && (mask >= DMA_40BIT_MASK)) { + printk(KERN_INFO "%s: Force SAC with mask %Lx\n", + dev->bus_id, mask); + return 0; + } + + return 1; +} +EXPORT_SYMBOL(dma_supported); + + static int __init pci_iommu_init(void) { #ifdef CONFIG_CALGARY_IOMMU |