summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/include
diff options
context:
space:
mode:
authorGavin Shan <gwshan@linux.vnet.ibm.com>2014-09-30 12:39:10 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2014-09-30 17:15:20 +1000
commitfe7e85c6f5ff63a8cd081deb35e58a0bd47589cd (patch)
tree65edbf090dcf8da262a0c729d126f50c15ed0823 /arch/powerpc/include
parent372fb80db93af5d85c750515526d731856e1890c (diff)
downloadop-kernel-dev-fe7e85c6f5ff63a8cd081deb35e58a0bd47589cd.zip
op-kernel-dev-fe7e85c6f5ff63a8cd081deb35e58a0bd47589cd.tar.gz
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 <mniyer@us.ibm.com> Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include')
-rw-r--r--arch/powerpc/include/asm/dma-mapping.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index 150866b..894d538 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -135,6 +135,7 @@ static inline int dma_supported(struct device *dev, u64 mask)
extern int dma_set_mask(struct device *dev, u64 dma_mask);
extern int __dma_set_mask(struct device *dev, u64 dma_mask);
+extern u64 __dma_get_required_mask(struct device *dev);
#define dma_alloc_coherent(d,s,h,f) dma_alloc_attrs(d,s,h,f,NULL)
OpenPOWER on IntegriCloud