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Message-Id: <20180415090808.19121-3-tiwai@suse.de> Date: Sun, 15 Apr 2018 11:08:08 +0200 From: Takashi Iwai <tiwai@...e.de> To: Christoph Hellwig <hch@....de> Cc: iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org Subject: [PATCH 2/2] swiotlb: Fix dma_supported() to consider direct allocation Along with the recent change to use the common swiotlb dma_ops, x86 also takes over the swiotlb_dma_supported(). This caused a regression when a low bit DMA mask is set; e.g. parport_pc driver now fails to set the 24bit DMA mask: parport_pc parport_pc.956: Unable to set coherent dma mask: disabling DMA It's because swiotlb_dma_supported() only checks the swiotlb range, and the 24bit DMA mask is below io_tlb_end. OTOH, in the past kernel versions, x86's swiotlb dma_supported() was NULL, which was effectively evaluated as the direct DMA, hence the lower DMA mask was allowed. This patch fixes the regression by extending swiotlb_dma_supported() to check the direct DMA at first for covering the primary allocation before swiotlb. Fixes: 6e4bf5867783 ("x86/dma: Use generic swiotlb_ops") Signed-off-by: Takashi Iwai <tiwai@...e.de> --- lib/swiotlb.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/swiotlb.c b/lib/swiotlb.c index de7cc540450f..a81502ea79e7 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -1042,6 +1042,10 @@ swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr) int swiotlb_dma_supported(struct device *hwdev, u64 mask) { +#ifdef CONFIG_DMA_DIRECT_OPS + if (dma_direct_supported(hwdev, mask)) + return 1; +#endif return __phys_to_dma(hwdev, io_tlb_end - 1) <= mask; } -- 2.16.3
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