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-rw-r--r-- | Documentation/DMA-mapping.txt | 20 |
1 files changed, 0 insertions, 20 deletions
diff --git a/Documentation/DMA-mapping.txt b/Documentation/DMA-mapping.txt index 3c8ae020b6a7..d84f89dbf921 100644 --- a/Documentation/DMA-mapping.txt +++ b/Documentation/DMA-mapping.txt | |||
@@ -189,12 +189,6 @@ smaller mask as pci_set_dma_mask(). However for the rare case that a | |||
189 | device driver only uses consistent allocations, one would have to | 189 | device driver only uses consistent allocations, one would have to |
190 | check the return value from pci_set_consistent_dma_mask(). | 190 | check the return value from pci_set_consistent_dma_mask(). |
191 | 191 | ||
192 | If your 64-bit device is going to be an enormous consumer of DMA | ||
193 | mappings, this can be problematic since the DMA mappings are a | ||
194 | finite resource on many platforms. Please see the "DAC Addressing | ||
195 | for Address Space Hungry Devices" section near the end of this | ||
196 | document for how to handle this case. | ||
197 | |||
198 | Finally, if your device can only drive the low 24-bits of | 192 | Finally, if your device can only drive the low 24-bits of |
199 | address during PCI bus mastering you might do something like: | 193 | address during PCI bus mastering you might do something like: |
200 | 194 | ||
@@ -203,8 +197,6 @@ address during PCI bus mastering you might do something like: | |||
203 | "mydev: 24-bit DMA addressing not available.\n"); | 197 | "mydev: 24-bit DMA addressing not available.\n"); |
204 | goto ignore_this_device; | 198 | goto ignore_this_device; |
205 | } | 199 | } |
206 | [Better use DMA_24BIT_MASK instead of 0x00ffffff. | ||
207 | See linux/include/dma-mapping.h for reference.] | ||
208 | 200 | ||
209 | When pci_set_dma_mask() is successful, and returns zero, the PCI layer | 201 | When pci_set_dma_mask() is successful, and returns zero, the PCI layer |
210 | saves away this mask you have provided. The PCI layer will use this | 202 | saves away this mask you have provided. The PCI layer will use this |
@@ -652,18 +644,6 @@ It is planned to completely remove virt_to_bus() and bus_to_virt() as | |||
652 | they are entirely deprecated. Some ports already do not provide these | 644 | they are entirely deprecated. Some ports already do not provide these |
653 | as it is impossible to correctly support them. | 645 | as it is impossible to correctly support them. |
654 | 646 | ||
655 | 64-bit DMA and DAC cycle support | ||
656 | |||
657 | Do you understand all of the text above? Great, then you already | ||
658 | know how to use 64-bit DMA addressing under Linux. Simply make | ||
659 | the appropriate pci_set_dma_mask() calls based upon your cards | ||
660 | capabilities, then use the mapping APIs above. | ||
661 | |||
662 | It is that simple. | ||
663 | |||
664 | Well, not for some odd devices. See the next section for information | ||
665 | about that. | ||
666 | |||
667 | Optimizing Unmap State Space Consumption | 647 | Optimizing Unmap State Space Consumption |
668 | 648 | ||
669 | On many platforms, pci_unmap_{single,page}() is simply a nop. | 649 | On many platforms, pci_unmap_{single,page}() is simply a nop. |