linux-kernel - [PATCH 04/12] x86: make dma_cache

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Message-Id: <20170827161032.22772-5-hch@lst.de>
Date:   Sun, 27 Aug 2017 18:10:24 +0200
From:   Christoph Hellwig <hch@....de>
To:     iommu@...ts.linux-foundation.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Michal Simek <monstr@...str.eu>,
        David Howells <dhowells@...hat.com>,
        Guan Xuetao <gxt@...c.pku.edu.cn>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>, x86@...nel.org,
        linux-mips@...ux-mips.org, linux-ia64@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-xtensa@...ux-xtensa.org,
        linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: [PATCH 04/12] x86: make dma_cache_sync a no-op

x86 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
make any sense to do any work in dma_cache_sync given that it must be a
no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@....de
---
 arch/x86/include/asm/dma-mapping.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index 398c79889f5c..04877267ad18 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -70,7 +70,6 @@ static inline void
 dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 	enum dma_data_direction dir)
 {
-	flush_write_buffers();
 }
 
 static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
-- 
2.11.0