Hi Geert, Thank you for the patch.
On Friday 27 Jan 2017 16:34:19 Geert Uytterhoeven wrote: > Add support for allocation physically contiguous DMA buffers on arm64 > systems with an IOMMU, by dispatching DMA buffer allocations with the > DMA_ATTR_FORCE_CONTIGUOUS attribute to the appropriate IOMMU DMA > helpers. > > Note that as this uses the CMA allocator, setting this attribute has a > runtime-dependency on CONFIG_DMA_CMA, just like on arm32. > > For arm64 systems using swiotlb, no changes are needed to support the > allocation of physically contiguous DMA buffers: > - swiotlb always uses physically contiguous buffers (up to > IO_TLB_SEGSIZE = 128 pages), > - arm64's __dma_alloc_coherent() already calls > dma_alloc_from_contiguous() when CMA is available. > > Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be> > --- > v2: > - New, handle dispatching in the arch (arm64) code, as requested by > Robin Murphy. > --- > arch/arm64/mm/dma-mapping.c | 51 +++++++++++++++++++++++++++++------------- > 1 file changed, 37 insertions(+), 14 deletions(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index 1d7d5d2881db7c19..325803e0ba79ef26 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -577,20 +577,7 @@ static void *__iommu_alloc_attrs(struct device *dev, > size_t size, */ > gfp |= __GFP_ZERO; > > - if (gfpflags_allow_blocking(gfp)) { > - struct page **pages; > - pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, coherent); > - > - pages = iommu_dma_alloc(dev, iosize, gfp, attrs, ioprot, > - handle, flush_page); > - if (!pages) > - return NULL; > - > - addr = dma_common_pages_remap(pages, size, VM_USERMAP, prot, > - __builtin_return_address(0)); > - if (!addr) > - iommu_dma_free(dev, pages, iosize, handle); > - } else { > + if (!gfpflags_allow_blocking(gfp)) { > struct page *page; > /* > * In atomic context we can't remap anything, so we'll only > @@ -614,6 +601,35 @@ static void *__iommu_alloc_attrs(struct device *dev, > size_t size, __free_from_pool(addr, size); > addr = NULL; > } > + } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) { > + pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, coherent); > + struct page *page; > + > + page = iommu_dma_alloc_contiguous(dev, iosize, ioprot, handle); > + if (!page) > + return NULL; > + > + if (!coherent) > + __dma_flush_area(page_to_virt(page), iosize); > + > + addr = dma_common_contiguous_remap(page, size, VM_USERMAP, > + prot, > + __builtin_return_address(0)); > + if (!addr) > + iommu_dma_free_contiguous(dev, page, iosize, handle); > + } else { > + pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, coherent); > + struct page **pages; > + > + pages = iommu_dma_alloc(dev, iosize, gfp, attrs, ioprot, > + handle, flush_page); > + if (!pages) > + return NULL; > + > + addr = dma_common_pages_remap(pages, size, VM_USERMAP, prot, > + __builtin_return_address(0)); > + if (!addr) > + iommu_dma_free(dev, pages, iosize, handle); > } > return addr; > } > @@ -626,6 +642,8 @@ static void __iommu_free_attrs(struct device *dev, > size_t size, void *cpu_addr, size = PAGE_ALIGN(size); > /* > * @cpu_addr will be one of 3 things depending on how it was allocated: s/one of 3/one of 4/ Apart from that, Acked-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com> > + * - A remapped array of pages from iommu_dma_alloc_contiguous() > + * for contiguous allocations. > * - A remapped array of pages from iommu_dma_alloc(), for all > * non-atomic allocations. > * - A non-cacheable alias from the atomic pool, for atomic > @@ -637,6 +655,11 @@ static void __iommu_free_attrs(struct device *dev, > size_t size, void *cpu_addr, if (__in_atomic_pool(cpu_addr, size)) { > iommu_dma_unmap_page(dev, handle, iosize, 0, 0); > __free_from_pool(cpu_addr, size); > + } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) { > + struct page *page = phys_to_page(dma_to_phys(dev, handle)); > + > + iommu_dma_free_contiguous(dev, page, iosize, &handle); > + dma_common_free_remap(cpu_addr, size, VM_USERMAP); > } else if (is_vmalloc_addr(cpu_addr)){ > struct vm_struct *area = find_vm_area(cpu_addr); -- Regards, Laurent Pinchart