On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote: > On 8/6/2014 1:17 PM, Joerg Roedel wrote: > > On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote: > >> so you are suggesting that I check in "bus_set_iommu()" whether the > >> driver has set the map_sg/unmap_sg function pointers or not and if not > >> set it to the default? Is bus_set_iommu() the only way drivers can set > >> up the callbacks? > > > > This doesn't work as the iommu_ops are now const. You have to either > > update the iommu drivers individually to point to the default function, > > or you do the check in the API function itself and fall back to the > > default it no call-back is provided. > > > > Ok, then I think it is better to just leave the fallback where it is now > in the function itself. What Konrad was suggesting is what I also proposed. The idea is to implement a fallback as standalone function, then make all drivers use that by default in the struct iommu_ops that they register. When drivers implement an optimized version they can simply replace the fallback implementation with their own. Thierry
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