Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-07-16 Thread Robin Murphy
On 2021-07-16 07:24, Christoph Hellwig wrote: On Wed, Jul 14, 2021 at 07:19:50PM +0100, Robin Murphy wrote: Even at the DMA API level you could hide *some* of it (at the cost of effectively only having 1/4 of the usable address space), but there are still cases like where v4l2 has a hard

Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-07-16 Thread Christoph Hellwig
On Wed, Jul 14, 2021 at 07:19:50PM +0100, Robin Murphy wrote: > Even at the DMA API level you could hide *some* of it (at the cost of > effectively only having 1/4 of the usable address space), but there are > still cases like where v4l2 has a hard requirement that a page-aligned > scatterlist can

Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-07-15 Thread Joerg Roedel
On Wed, Jul 14, 2021 at 10:51:34PM +0200, Arnd Bergmann wrote: > The question is how we can best allow one but not the other. By only allowing to allocate domains of type IDENTITY and DMA, but fail to allocate UNMANAGED domains. Regards, Joerg

Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-07-14 Thread Arnd Bergmann
On Wed, Jul 14, 2021 at 8:21 PM Robin Murphy wrote: > > On 2021-06-27 15:34, Sven Peter wrote: > [...] > > In the long term, I'd like to extend the dma-iommu framework itself to > > support iommu pagesizes with a larger granule than the CPU pagesize if that > > is > > something you agree with. >

Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-07-14 Thread Robin Murphy
On 2021-06-27 15:34, Sven Peter wrote: [...] In the long term, I'd like to extend the dma-iommu framework itself to support iommu pagesizes with a larger granule than the CPU pagesize if that is something you agree with. BTW this isn't something we can fully support in general. IOMMU API

[PATCH v4 0/3] Apple M1 DART IOMMU driver

2021-06-27 Thread Sven Peter via iommu
Hi, This is v4 of my Apple M1 DART IOMMU driver series as a follow up to the previous versions [1][2][3]. Short summary: this series adds support for the iommu found in Apple's new M1 SoC which is required to use DMA on most peripherals like the display controller, the USB ports or the