netdev - [mm PATCH v2 04/26] arch/arc: Add option to skip sync on DMA mapping

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Date:   Wed, 02 Nov 2016 07:13:11 -0400
From:   Alexander Duyck <alexander.h.duyck@...el.com>
To:     linux-mm@...ck.org, akpm@...ux-foundation.org
Cc:     Vineet Gupta <vgupta@...opsys.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [mm PATCH v2 04/26] arch/arc: Add option to skip sync on DMA mapping

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
later via a sync_for_cpu or sync_for_device call.

Acked-by: Vineet Gupta <vgupta@...opsys.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---
 arch/arc/mm/dma.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 60aab5a..ea207d2 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -133,7 +133,10 @@ static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page,
 		unsigned long attrs)
 {
 	phys_addr_t paddr = page_to_phys(page) + offset;
-	_dma_cache_sync(paddr, size, dir);
+
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		_dma_cache_sync(paddr, size, dir);
+
 	return plat_phys_to_dma(dev, paddr);
 }