linux-kernel - [PATCH 13/14] staging: android: ion: Do not sync CPU cache on map/unmap

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Date:   Fri, 11 Jan 2019 12:05:22 -0600
From:   "Andrew F. Davis" <afd@...com>
To:     Laura Abbott <labbott@...hat.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arve Hjønnevåg <arve@...roid.com>
CC:     <devel@...verdev.osuosl.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>, "Andrew F . Davis" <afd@...com>
Subject: [PATCH 13/14] staging: android: ion: Do not sync CPU cache on map/unmap

Buffers may not be mapped from the CPU so skip cache maintenance here.
Accesses from the CPU to a cached heap should be bracketed with
{begin,end}_cpu_access calls so maintenance should not be needed anyway.

Signed-off-by: Andrew F. Davis <afd@...com>
---
 drivers/staging/android/ion/ion.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 14e48f6eb734..09cb5a8e2b09 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -261,8 +261,8 @@ static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment,
 
 	table = a->table;
 
-	if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
-			direction))
+	if (!dma_map_sg_attrs(attachment->dev, table->sgl, table->nents,
+			      direction, DMA_ATTR_SKIP_CPU_SYNC))
 		return ERR_PTR(-ENOMEM);
 
 	return table;
@@ -272,7 +272,8 @@ static void ion_unmap_dma_buf(struct dma_buf_attachment *attachment,
 			      struct sg_table *table,
 			      enum dma_data_direction direction)
 {
-	dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+	dma_unmap_sg_attrs(attachment->dev, table->sgl, table->nents,
+			   direction, DMA_ATTR_SKIP_CPU_SYNC);
 }
 
 static int ion_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
-- 
2.19.1