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
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