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[IA64] SN specific version of dma_get_required_mask()

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Create a platform specific version of dma_get_required_mask()
for ia64 SN Altix. All SN Altix platforms support 64 bit DMA
addressing regardless of the size of system memory.
Create an ia64 machvec for dma_get_required_mask, with the
SN version unconditionally returning DMA_64BIT_MASK.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
John Keller
2008-11-24 16:47:17 -06:00
committed by Tony Luck
parent a6a3bb5c88
commit 175add1981
7 changed files with 49 additions and 5 deletions
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9
Documentation/DMA-API.txt
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@@ -170,16 +170,15 @@ Returns: 0 if successful and a negative error if not.
u64
dma_get_required_mask(struct device *dev)
After setting the mask with dma_set_mask(), this API returns the
actual mask (within that already set) that the platform actually
requires to operate efficiently. Usually this means the returned mask
This API returns the mask that the platform requires to
operate efficiently. Usually this means the returned mask
is the minimum required to cover all of memory. Examining the
required mask gives drivers with variable descriptor sizes the
opportunity to use smaller descriptors as necessary.
Requesting the required mask does not alter the current mask. If you
wish to take advantage of it, you should issue another dma_set_mask()
call to lower the mask again.
wish to take advantage of it, you should issue a dma_set_mask()
call to set the mask to the value returned.
Part Id - Streaming DMA mappings