Hello all, We pretty much tried to solve the same issue here with a new API in DMA-IOMMU: https://lore.kernel.org/linux-iommu/20200811054912.GA301@xxxxxxxxxxxxx/T/ Christopher- the user part would be MFC devices on exynos platforms Thanks, Ajay On 9/23/20, Christoph Hellwig <hch@xxxxxx> wrote: > On Wed, Sep 23, 2020 at 08:48:26AM +0200, Marek Szyprowski wrote: >> Hi Shaik, >> >> I've run into similar problem while adapting S5P-MFC and Exynos4-IS >> drivers for generic IOMMU-DMA framework. Here is my first solution: >> https://lore.kernel.org/linux-samsung-soc/20200918144833.14618-1-m.szyprowski@xxxxxxxxxxx/T/ >> >> >> >> It allows to remap given buffer at the specific IOVA address, although >> it doesn't guarantee that those specific addresses won't be later used >> by the IOVA allocator. Probably it would make sense to add an API for >> generic IOMMU-DMA framework to mark the given IOVA range as >> reserved/unused to protect them. > > If you want to use IOVA addresses in a device otherwise managed by > dma-iommu we need to expose an API through the dma API. Can you please > include the iommu list in the discussion of your series? > > I don't think using the raw IOMMU API is a very idea in these drivers, > we probably want a way to change the allocator algorithm or hint the > next IOVA and keep using the normal DMA API. Maybe Robin has a better > idea. >
