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The current PowerPC code makes pci_unmap_addr(), pci_unmap_addr_set(), and friends trivial for all 32-bit kernels. This is reasonable, since for those kernels it is true that pci_unmap_single() does not need the DMA address from the original DMA mapping -- in fact, it is a NOP. However, I recently tried the tg3 driver on a PowerPC 440SPe machine, which runs a 32-bit kernel and has non-cache-coherent PCI DMA. I found that the tg3 driver crashed in pci_dma_sync_single_for_cpu(), since for non-coherent systems, that function must invalidate the cache for the DMA address range requested, and therefore it does use the address passed in. tg3 uses a DMA address it stashes away with pci_unmap_addr_set() and retrieves with pci_unmap_addr(). Of course, since pci_unmap_addr() is defined to (0) right now, this doesn't work. It seems to me that the tg3 driver is using pci_unmap_addr() in a legitimate way -- I wouldn't want to have to teach all drivers that they should use pci_unmap_addr() if they only need the address for unmapping functions, but if they want the pci_dma_sync functions, then they have to store the DMA address without the helper macros. The right fix therefore seems to be in the definition of the macros in <asm/pci.h> -- we should use the trivial versions only for 32-bit kernels for coherent systems, and the real versions for both 64-bit kernels and non-coherent systems. Signed-off-by: Roland Dreier <rolandd@cisco.com> Signed-off-by: Paul Mackerras <paulus@samba.org> |
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| asm-generic | ||
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| asm-m68knommu | ||
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| asm-parisc | ||
| asm-powerpc | ||
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| asm-sh | ||
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| crypto | ||
| keys | ||
| linux | ||
| math-emu | ||
| media | ||
| mtd | ||
| net | ||
| pcmcia | ||
| rdma | ||
| rxrpc | ||
| scsi | ||
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| Kbuild | ||