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| author | Christoph Hellwig <hch@lst.de> | 2018-01-09 23:39:03 +0100 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2018-01-15 09:35:12 +0100 |
| commit | c61e9637340e1d0672c6f0c0b11aa81d7262c49d (patch) | |
| tree | 2e38215dba2ec8b18ac7f89e4a24c0a0b7da7b52 /lib | |
| parent | 21f237e4d08511eb662b59d8ff1b64be68e0c2bc (diff) | |
| download | linux-c61e9637340e1d0672c6f0c0b11aa81d7262c49d.tar.bz2 | |
dma-direct: add support for allocation from ZONE_DMA and ZONE_DMA32
This allows to dip into zones for lower memory if they are available.
If one of the zones is not available the corresponding GFP_* flag
will evaluate to 0 so they won't change anything. We provide an
arch tunable for those architectures that do not use GFP_DMA for
the lowest 24-bits, given that there are a few.
Roughly based on the x86 code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/dma-direct.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/dma-direct.c b/lib/dma-direct.c index f04a424f91fa..8f76032ebc3c 100644 --- a/lib/dma-direct.c +++ b/lib/dma-direct.c @@ -12,6 +12,14 @@ #define DIRECT_MAPPING_ERROR 0 +/* + * Most architectures use ZONE_DMA for the first 16 Megabytes, but + * some use it for entirely different regions: + */ +#ifndef ARCH_ZONE_DMA_BITS +#define ARCH_ZONE_DMA_BITS 24 +#endif + static bool check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, const char *caller) @@ -34,6 +42,12 @@ static void *dma_direct_alloc(struct device *dev, size_t size, int page_order = get_order(size); struct page *page = NULL; + /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */ + if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) + gfp |= GFP_DMA; + if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) + gfp |= GFP_DMA32; + /* CMA can be used only in the context which permits sleeping */ if (gfpflags_allow_blocking(gfp)) page = dma_alloc_from_contiguous(dev, count, page_order, gfp); |