From fe7e85c6f5ff63a8cd081deb35e58a0bd47589cd Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Tue, 30 Sep 2014 12:39:10 +1000 Subject: powerpc/powernv: Override dma_get_required_mask() The dma_get_required_mask() function is used by some drivers to query the platform about what DMA mask is needed to cover all of memory. This is a bit of a strange semantic when we have to choose between IOMMU translation or bypass, but essentially what it means is "what DMA mask will give best performances". Currently, our IOMMU backend always returns a 32-bit mask here, we don't do anything special to it when we have bypass available. This causes some drivers to choose a 32-bit mask, thus losing the ability to use the bypass window, thinking this is more efficient. The problem was reported from the driver of following device: 0004:03:00.0 0107: 1000:0087 (rev 05) 0004:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios \ Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05) This patch adds an override of that function in order to, instead, return a 64-bit mask whenever a bypass window is available in order for drivers to prefer this configuration. Reported-by: Murali N. Iyer Suggested-by: Benjamin Herrenschmidt Signed-off-by: Gavin Shan Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/powernv/pci.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/platforms/powernv/pci.h') diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h index 27594cf7f76d..34d29eb2a4de 100644 --- a/arch/powerpc/platforms/powernv/pci.h +++ b/arch/powerpc/platforms/powernv/pci.h @@ -124,6 +124,8 @@ struct pnv_phb { void (*dma_dev_setup)(struct pnv_phb *phb, struct pci_dev *pdev); int (*dma_set_mask)(struct pnv_phb *phb, struct pci_dev *pdev, u64 dma_mask); + u64 (*dma_get_required_mask)(struct pnv_phb *phb, + struct pci_dev *pdev); void (*fixup_phb)(struct pci_controller *hose); u32 (*bdfn_to_pe)(struct pnv_phb *phb, struct pci_bus *bus, u32 devfn); void (*shutdown)(struct pnv_phb *phb); -- cgit v1.2.3