diff options
| author | Christoph Hellwig <hch@lst.de> | 2018-09-07 09:31:58 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2018-10-01 07:31:25 -0700 |
| commit | 9d7a224b463e1cf1178570b57b6497240fd79bc3 (patch) | |
| tree | ae0c4b9399057288e7a715fb066c8a5edc71154b | |
| parent | b4ebe6063204da58e48600b810a97c29ae9e5d12 (diff) | |
| download | linux-9d7a224b463e1cf1178570b57b6497240fd79bc3.tar.bz2 | |
dma-direct: always allow dma mask <= physiscal memory size
This way an architecture with less than 4G of RAM can support dma_mask
smaller than 32-bit without a ZONE_DMA. Apparently that is a common
case on powerpc.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
| -rw-r--r-- | kernel/dma/direct.c | 28 |
1 files changed, 16 insertions, 12 deletions
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 60c433b880e0..170bd322a94a 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -284,21 +284,25 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, return nents; } +/* + * Because 32-bit DMA masks are so common we expect every architecture to be + * able to satisfy them - either by not supporting more physical memory, or by + * providing a ZONE_DMA32. If neither is the case, the architecture needs to + * use an IOMMU instead of the direct mapping. + */ int dma_direct_supported(struct device *dev, u64 mask) { -#ifdef CONFIG_ZONE_DMA - if (mask < phys_to_dma(dev, DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))) - return 0; -#else - /* - * Because 32-bit DMA masks are so common we expect every architecture - * to be able to satisfy them - either by not supporting more physical - * 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 < phys_to_dma(dev, DMA_BIT_MASK(32))) + u64 min_mask; + + if (IS_ENABLED(CONFIG_ZONE_DMA)) + min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS); + else + min_mask = DMA_BIT_MASK(32); + + min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT); + + if (mask >= phys_to_dma(dev, min_mask)) return 0; -#endif return 1; } |