netdev - [net-next PATCH RFC 21/26] arch/xtensa: Add option to skip DMA sync as a part of mapping

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Message-ID: <20161024120617.16276.40617.stgit@ahduyck-blue-test.jf.intel.com>
Date:   Mon, 24 Oct 2016 08:06:17 -0400
From:   Alexander Duyck <alexander.h.duyck@...el.com>
To:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     Max Filippov <jcmvbkbc@...il.com>, davem@...emloft.net,
        brouer@...hat.com
Subject: [net-next PATCH RFC 21/26] arch/xtensa: Add option to skip DMA sync
 as a part of 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
via a sync_for_cpu or sync_for_device call.

Cc: Max Filippov <jcmvbkbc@...il.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---
 arch/xtensa/kernel/pci-dma.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index 1e68806..6a16dec 100644
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -189,7 +189,9 @@ static dma_addr_t xtensa_map_page(struct device *dev, struct page *page,
 {
 	dma_addr_t dma_handle = page_to_phys(page) + offset;
 
-	xtensa_sync_single_for_device(dev, dma_handle, size, dir);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		xtensa_sync_single_for_device(dev, dma_handle, size, dir);
+
 	return dma_handle;
 }
 
@@ -197,7 +199,8 @@ static void xtensa_unmap_page(struct device *dev, dma_addr_t dma_handle,
 			      size_t size, enum dma_data_direction dir,
 			      unsigned long attrs)
 {
-	xtensa_sync_single_for_cpu(dev, dma_handle, size, dir);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		xtensa_sync_single_for_cpu(dev, dma_handle, size, dir);
 }
 
 static int xtensa_map_sg(struct device *dev, struct scatterlist *sg,