Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d1482f40c975e883f209aab659ec75a0afd84075
Commit: d1482f40c975e883f209aab659ec75a0afd84075
Parent: 814073620a2eb520c8bb38e0038fd1c78011fe21
Author: Matthew Wilcox <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 23:31:27 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Oct 17 08:43:06 2007 -0700
Update DMA-mapping documentation
A couple of updates haven't considered whether the documentation makes
sense as a whole any more. Three changes here:
- Remove the reference to the "DAC Addressing for Address Space Hungry
Devices" section which was deleted by Jan Beulich.
- Remove the comment about DMA_24BIT_MASK which became obsolete when
Tobias Klauser changed the code to actually use DMA_24BIT_MASK.
- Remove the section "64-bit DMA and DAC cycle support" since it's
fully covered above, and contains a reference to the section deleted
by Jan.
Signed-off-by: Matthew Wilcox <[EMAIL PROTECTED]>
Cc: "David S. Miller" <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
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 3c8ae02..d84f89d 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.
-
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