Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2019-08-05 09:10:58
Also in:
linux-arm-kernel, linux-iommu, linux-mips, lkml
On Mon, Aug 05, 2019 at 11:01:44AM +0300, Christoph Hellwig wrote:
All the way back to introducing dma_common_mmap we've defaulyed to mark
s/defaultyed/defaulted/
the pages as uncached. But this is wrong for DMA coherent devices. Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that flag is only treated special on the alloc side for non-coherent devices. Introduce a new dma_pgprot helper that deals with the check for coherent devices so that only the remapping cases even reach arch_dma_mmap_pgprot
s/even/ever/
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 1d3f0b5a9940..bd2b039f43a6 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c@@ -14,9 +14,7 @@ pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs) { - if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE)) - return pgprot_writecombine(prot); - return prot; + return pgprot_writecombine(prot); }
For arm64: Acked-by: Catalin Marinas <catalin.marinas@arm.com>