On 24/08/18 07:53, Christoph Hellwig wrote:
When a device has a DMA offset the dma capable result will change due to the difference between the physical and DMA address. Take that into account.
The "phys_to_dma(..., DMA_BIT_MASK(...))" idiom always looks like a glaring error at first glance, but this whole function is fairly unintuitive anyway, and ultimately I think the change does work out to be correct.
It might be nicer if we could reference max_zone_pfns[] for a bit more clarity, but I guess that's not arch-independent.
Reviewed-by: Robin Murphy <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]> Reviewed-by: Benjamin Herrenschmidt <[email protected]> --- kernel/dma/direct.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 1c35b7b945d0..de87b0282e74 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -168,7 +168,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, int dma_direct_supported(struct device *dev, u64 mask) { #ifdef CONFIG_ZONE_DMA - if (mask < DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) + if (mask < phys_to_dma(dev, DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))) return 0; #else /* @@ -177,7 +177,7 @@ int dma_direct_supported(struct device *dev, u64 mask) * memory, or by providing a ZONE_DMA32. If neither is the case, the * architecture needs to use an IOMMU instead of the direct mapping. */ - if (mask < DMA_BIT_MASK(32)) + if (mask < phys_to_dma(dev, DMA_BIT_MASK(32))) return 0; #endif /*
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