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a79a812131
We used to use generic implementation of dma_map_ops.mmap which is dma_common_mmap() but that only worked for simpler cached mappings when vaddr = paddr. If a driver requests uncached DMA buffer kernel maps it to virtual address so that MMU gets involved and page uncached status takes into account. In that case usage of dma_common_mmap() lead to mapping of vaddr to vaddr for user-space which is obviously wrong. For more detals please refer to verbose explanation here [1]. So here we implement our own version of mmap() which always deals with dma_addr and maps underlying memory to user-space properly (note that DMA buffer mapped to user-space is always uncached because there's no way to properly manage cache from user-space). [1] https://lkml.org/lkml/2016/10/26/973 Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: <stable@vger.kernel.org> #4.5+ Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> |
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