Messages in this thread | ![/](/images/icornerl.gif) | | From | Christoph Hellwig <> | Subject | generic DMA bypass flag v2 | Date | Fri, 20 Mar 2020 15:16:38 +0100 |
| |
Hi all,
I've recently beeing chatting with Lu about using dma-iommu and per-device DMA ops in the intel IOMMU driver, and one missing feature in dma-iommu is a bypass mode where the direct mapping is used even when an iommu is attached to improve performance. The powerpc code already has a similar mode, so I'd like to move it to the core DMA mapping code. As part of that I noticed that the current powerpc code has a little bug in that it used the wrong check in the dma_sync_* routines to see if the direct mapping code is used.
These two patches just add the generic code and move powerpc over, the intel IOMMU bits will require a separate discussion.
The x86 AMD Gart code also has a bypass mode, but it is a lot strange, so I'm not going to touch it for now.
Changes since v1: - rebased to the current dma-mapping-for-next tree
| ![\](/images/icornerr.gif) |