* [mm PATCH v2 18/26] arch/powerpc: Add option to skip DMA sync as a part of mapping
[not found] <20161102111031.79519.14741.stgit@ahduyck-blue-test.jf.intel.com>
@ 2016-11-02 11:15 ` Alexander Duyck
2016-11-04 3:16 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Duyck @ 2016-11-02 11:15 UTC (permalink / raw)
To: linux-mm, akpm
Cc: Benjamin Herrenschmidt, linux-kernel, Paul Mackerras,
Michael Ellerman, netdev, linuxppc-dev
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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
arch/powerpc/kernel/dma.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index e64a601..6877e3f 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -203,6 +203,10 @@ static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
for_each_sg(sgl, sg, nents, i) {
sg->dma_address = sg_phys(sg) + get_dma_offset(dev);
sg->dma_length = sg->length;
+
+ if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+ continue;
+
__dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
}
@@ -235,7 +239,10 @@ static inline dma_addr_t dma_direct_map_page(struct device *dev,
unsigned long attrs)
{
BUG_ON(dir == DMA_NONE);
- __dma_sync_page(page, offset, size, dir);
+
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ __dma_sync_page(page, offset, size, dir);
+
return page_to_phys(page) + offset + get_dma_offset(dev);
}
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