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    x86: use GFP_DMA for 24bit coherent_dma_mask · 75bebb7f
    FUJITA Tomonori 提交于
    dma_alloc_coherent (include/asm-x86/dma-mapping.h) avoids GFP_DMA
    allocation first and if the allocated address is not fit for the
    device's coherent_dma_mask, then dma_alloc_coherent does GFP_DMA
    allocation. This is because dma_alloc_coherent avoids precious GFP_DMA
    zone if possible. This is also how the old dma_alloc_coherent
    (arch/x86/kernel/pci-dma.c) works.
    
    However, if the coherent_dma_mask of a device is 24bit, there is no
    point to go into the above GFP_DMA retry mechanism. We had better use
    GFP_DMA in the first place.
    Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
    Tested-by: NTakashi Iwai <tiwai@suse.de>
    Signed-off-by: NIngo Molnar <mingo@elte.hu>
    75bebb7f
dma-mapping.h 8.4 KB