20 Jun
2013
20 Jun
'13
10:13 a.m.
On Thursday 20 June 2013, Hiroshi Doyu wrote:
If devices allocate via dma-mapping API, physical mem allocation, iova allocation and iommu mapping happens internally. Devices may allocate physical memory using any allocator (say ION including carveout area), use "iommu mapping" API which will do iova allocation and iommu mapping. The prot flags could be useful in this case as well - not sure whether we would need dma-attrs here.
I haven't followed ION recently, but can't ION backed by DMA mapping API instead of using IOMMU API directly?
For a GPU with an IOMMU, you typically want per-process IOMMU contexts, which are only available when using the IOMMU API directly, as the dma-mapping abstraction uses only one context for kernel space.
Arnd