[PATCH V2 0/6] IOMMU-DMA - support DMA_ATTR_LOW_ADDRESS attribute

[Ajay Kumar]

Ping!

On Thu, May 12, 2022 at 9:09 AM Ajay Kumar <ajaykumar.rs at samsung.com> wrote:
>
> This patchset is a rebase of original patches from Marek Szyprowski:
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2321261.html
>
> The patches have been rebased on Joro's IOMMU tree "next" branch:
> https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git
>
> This patchset is needed to address the IOVA address dependency issue between
> firmware buffers and other buffers in Samsung s5p-mfc driver.
>
> There have been few discussions in the past on how to find a generic
> soultion for this issue, ranging from adding an entirely new API to choose
> IOVA window[1], to adding a DMA attribute DMA_ATTR_LOW_ADDRESS which handles
> buffer allocation from lower address[2].
> This is a continuation of initial work from Marek for approach [2].
> Patches have been tested with latest version of Samsung s5p-mfc driver.
>
> Changes since V1:
> [PATCH V2 1/6]
> - Rebase on latest tree.
>
> [PATCH V2 2/6]
> - Rebase on latest tree.
>   Added a missing check for iova_pfn in __iova_rcache_get()
>   Discard changes from drivers/iommu/intel/iommu.c which are not necessary
>
> [PATCH V2 3/6]
> - Rebase on latest tree.
>
> [PATCH V2 4/6]
> - Rebase on latest tree
>
> [PATCH V2 5/6]
> - Rebase on latest tree
>
> [PATCH V2 6/6]
> - Rebase on latest tree.
>
> Marek Szyprowski (6):
>   dma-mapping: add DMA_ATTR_LOW_ADDRESS attribute
>   iommu: iova: properly handle 0 as a valid IOVA address
>   iommu: iova: add support for 'first-fit' algorithm
>   iommu: dma-iommu: refactor iommu_dma_alloc_iova()
>   iommu: dma-iommu: add support for DMA_ATTR_LOW_ADDRESS
>   media: platform: s5p-mfc: use DMA_ATTR_LOW_ADDRESS
>
> References:
> [1]
> https://lore.kernel.org/linux-iommu/20200811054912.GA301@infradead.org/
>
> [2]
> https://lore.kernel.org/linux-mm/bff57cbe-2247-05e1-9059-d9c66d64c407@arm.com
>
>  drivers/iommu/dma-iommu.c                     | 77 +++++++++++-----
>  drivers/iommu/iova.c                          | 91 ++++++++++++++++++-
>  .../media/platform/samsung/s5p-mfc/s5p_mfc.c  |  8 +-
>  include/linux/dma-mapping.h                   |  6 ++
>  include/linux/iova.h                          |  3 +
>  5 files changed, 156 insertions(+), 29 deletions(-)
>
>
> base-commit: faf93cfaadfaaff2a5c35d6301b45aa2f6e4ddb2
> --
> 2.17.1
>