diff options
| author | Alexey Brodkin <abrodkin@synopsys.com> | 2016-11-03 18:06:13 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2016-11-03 10:01:07 -0700 |
| commit | a79a812131b07254c09cf325ec68c0d05aaed0b5 (patch) | |
| tree | 0b4d5bd96a3999319b2f4f6c31c558bcda35c1b0 | |
| parent | 8f6d9eb2a3f38f1acd04efa0aeb8b81f5373c923 (diff) | |
arc: Implement arch-specific dma_map_ops.mmap
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>