ARC: dma [non IOC]: fix arc_dma_sync_single_for_(device|cpu) (4c612add) · Commits · 戴 / test

ARC backend for dma_sync_single_for_(device|cpu) was broken as it was not honoring the @dir argument and simply forcing it based on the call: - arc_dma_sync_single_for_device(dir) assumed DMA_TO_DEVICE (cache wback) - arc_dma_sync_single_for_cpu(dir) assumed DMA_FROM_DEVICE (cache inv) This is not true given the DMA API programming model and has been discussed here [1] in some detail. Interestingly while the deficiency has been there forever, it only started showing up after 4.17 dma common ops rework, commit ("arc: fix arc_dma_{map,unmap}_page") which wired up these calls under the more commonly used dma_map_page API triggering the issue. [1]: https://lkml.org/lkml/2018/5/18/979 Fixes: commit ("arc: fix arc_dma_{map,unmap}_page") Cc: stable@kernel.org # v4.17+ Signed-off-by:

Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> Signed-off-by:

Vineet Gupta <vgupta@synopsys.com> [vgupta: reworked changelog]

arch/arc/mm/dma.c

+47 −2

Original line number	Diff line number	Diff line
		@@ -129,14 +129,59 @@ int arch_dma_mmap(struct device dev, struct vm_area_struct vma,
		return ret;
		}

		/*
		* Cache operations depending on function and direction argument, inspired by
		* https://lkml.org/lkml/2018/5/18/979
		* "dma_sync_*_for_cpu and direction=TO_DEVICE (was Re: [PATCH 02/20]
		* dma-mapping: provide a generic dma-noncoherent implementation)"
		*
		* \| map == for_device \| unmap == for_cpu
		* \|----------------------------------------------------------------
		* TO_DEV \| writeback writeback \| none none
		* FROM_DEV \| invalidate invalidate \| invalidate* invalidate*
		* BIDIR \| writeback+inv writeback+inv \| invalidate invalidate
		*
		* [*] needed for CPU speculative prefetches
		*
		* NOTE: we don't check the validity of direction argument as it is done in
		* upper layer functions (in include/linux/dma-mapping.h)
		*/

		void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
		size_t size, enum dma_data_direction dir)
		{
		switch (dir) {
		case DMA_TO_DEVICE:
		dma_cache_wback(paddr, size);
		break;

		case DMA_FROM_DEVICE:
		dma_cache_inv(paddr, size);
		break;

		case DMA_BIDIRECTIONAL:
		dma_cache_wback_inv(paddr, size);
		break;

		default:
		break;
		}
		}

		void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
		size_t size, enum dma_data_direction dir)
		{
		switch (dir) {
		case DMA_TO_DEVICE:
		break;

		/* FROM_DEVICE invalidate needed if speculative CPU prefetch only */
		case DMA_FROM_DEVICE:
		case DMA_BIDIRECTIONAL:
		dma_cache_inv(paddr, size);
		break;

		default:
		break;
		}
		}

Admin message