[RFC PATCH] powerpc: fix get_arch_dma_ops() for NTB devices

[Alexander Fomichev <fomichev.ru@gmail.com>]

get_dma_ops() falls into arch-dependant get_arch_dma_ops(), which
historically returns NULL on PowerPC. Therefore dma_set_mask() fails.
This affects Switchtec (and probably other) NTB devices, that they fail
to initialize.
The proposed patch should fix the issue.

---
 arch/powerpc/include/asm/dma-mapping.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index ebf6680..cb6ac96 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -70,14 +70,11 @@ extern struct dma_map_ops dma_iommu_ops;
 #endif
 extern const struct dma_map_ops dma_nommu_ops;
 
+extern const struct dma_map_ops *get_pci_dma_ops(void);
+
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
-	/* We don't handle the NULL dev case for ISA for now. We could
-	 * do it via an out of line call but it is not needed for now. The
-	 * only ISA DMA device we support is the floppy and we have a hack
-	 * in the floppy driver directly to get a device for us.
-	 */
-	return NULL;
+	return get_pci_dma_ops();
 }
 
 /*
-- 
2.7.4