[Cbe-oss-dev] [patch 11/11] powerpc/cell: Add DMA_ATTR_STRONG_ORDERING dma attribute and use in IOMMU code

[Michael Ellerman]

On Fri, 2008-07-04 at 21:05 +0200, arnd at arndb.de wrote:

> Introduce a new dma attriblue DMA_ATTR_STRONG_ORDERING to use strong ordering
> on DMA mappings in the Cell processor. Add the code to the Cell's IOMMU
> implementation to use this.
> 
> The current Cell IOMMU implementation sets the IOPTE_SO_RW bits in all IOTPEs
> (for both the dynamic and fixed mappings) which enforces strong ordering of
> both reads and writes. This patch makes the default behaviour weak ordering
> (the IOPTE_SO_RW bits not set) and to request a strongly ordered mapping the
> new DMA_ATTR_STRONG_ORDERING needs to be used.

We're sure that's safe?

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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