On 04/16/2016 05:02 AM, Nishanth Menon wrote:
On 04/15/2016 08:42 AM, Mark Brown wrote:
On 15 Apr 2016 2:41 p.m., "Nishanth Menon" <nm@ti.com mailto:nm@ti.com> wrote:
Mark,
On 04/15/2016 06:13 AM, Mark Brown wrote:
Current kernels have support for the IOMMU-DMA layer and use this to enable devices connected via IOMMUs to get appropriate DMA operations automatically. This makes system integration of IOMMU systems easier, especially when development is targeted at upstream. We intend to backport this feature to currently active LSKs where it is not present unless concerns are raised.
I am unfortunately having access issues(working on getting it resolved) of accessing the card. Meanwhile, just to clarify: are we stating 4.4LSK alone or 4.4, 4.1, 3.18 as well?
At least v4.1, need to double check on v3.18 - IIRC this is actually in v4.4 already.
For the following commits in the JIRA: 876945dbf6497c75 arm64: Hook up IOMMU dma_ops 13b8629f651164d7 arm64: Add IOMMU dma_ops
we do not believe we have an issue on 4.1 kernel for a backport. Thanks for the headsup.
CC to linaro-kernel and request comments on implement:
This commit (166bdbd2316116 iommu/arm-smmu: Add support for MSI on SMMUv3) depends on a huge MSI change on 4.2/4.3 which could cause PCI and MSI related driver changes.
Consider the following concern: 1, big effort to backport the MSI domain/list changes. 2, msi_desc struct change would cause MSI related downstream driver rewriting which works on 4.1 kernel. 3, I have no suitable arm64 board in hands, my test relay on Naresh who living in India. So the testing would become unbearable for such big changes.
So I want to skip this commit in the IOMMU backporting. and suggest using LSK 4.4 kernel if someone really want the platform MSI. Any comments?
-- Regards, Nishanth Menon