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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 3c8ae020b6a..d84f89dbf92 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 device driver only uses consistent allocations, one would have to check the return value from pci_set_consistent_dma_mask(). -If your 64-bit device is going to be an enormous consumer of DMA -mappings, this can be problematic since the DMA mappings are a -finite resource on many platforms. Please see the "DAC Addressing -for Address Space Hungry Devices" section near the end of this -document for how to handle this case. - Finally, if your device can only drive the low 24-bits of address during PCI bus mastering you might do something like: @@ -203,8 +197,6 @@ address during PCI bus mastering you might do something like: "mydev: 24-bit DMA addressing not available.\n"); goto ignore_this_device; } -[Better use DMA_24BIT_MASK instead of 0x00ffffff. -See linux/include/dma-mapping.h for reference.] When pci_set_dma_mask() is successful, and returns zero, the PCI layer 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 they are entirely deprecated. Some ports already do not provide these as it is impossible to correctly support them. - 64-bit DMA and DAC cycle support - -Do you understand all of the text above? Great, then you already -know how to use 64-bit DMA addressing under Linux. Simply make -the appropriate pci_set_dma_mask() calls based upon your cards -capabilities, then use the mapping APIs above. - -It is that simple. - -Well, not for some odd devices. See the next section for information -about that. - Optimizing Unmap State Space Consumption On many platforms, pci_unmap_{single,page}() is simply a nop. |