[PATCH v6 5/5] s5p-mfc: Set DMA_ATTR_ALLOC_SINGLE_PAGES

Douglas Anderson dianders at chromium.org
Mon Jan 11 09:30:27 PST 2016


We do video allocation all the time and we need it to be fast.  Plus TLB
efficiency isn't terribly important for video.

That means we want to set DMA_ATTR_ALLOC_SINGLE_PAGES.

See also the previous change ("ARM: dma-mapping: Use
DMA_ATTR_ALLOC_SINGLE_PAGES hint to optimize allocation").

Signed-off-by: Douglas Anderson <dianders at chromium.org>
---
Changes in v6:
- renamed DMA_ATTR_NO_HUGE_PAGE to DMA_ATTR_ALLOC_SINGLE_PAGES

Changes in v5:
- s5p-mfc patch new for v5

Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/media/platform/s5p-mfc/s5p_mfc.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
index 927ab4928779..421d25a1aec1 100644
--- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
+++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
@@ -1095,6 +1095,7 @@ static int s5p_mfc_alloc_memdevs(struct s5p_mfc_dev *dev)
 /* MFC probe function */
 static int s5p_mfc_probe(struct platform_device *pdev)
 {
+	DEFINE_DMA_ATTRS(attrs);
 	struct s5p_mfc_dev *dev;
 	struct video_device *vfd;
 	struct resource *res;
@@ -1164,12 +1165,20 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 		}
 	}
 
-	dev->alloc_ctx[0] = vb2_dma_contig_init_ctx(dev->mem_dev_l);
+	/*
+	 * We'll do mostly sequential access, so sacrifice TLB efficiency for
+	 * faster allocation.
+	 */
+	dma_set_attr(DMA_ATTR_ALLOC_SINGLE_PAGES, &attrs);
+
+	dev->alloc_ctx[0] = vb2_dma_contig_init_ctx_attrs(dev->mem_dev_l,
+							  &attrs);
 	if (IS_ERR(dev->alloc_ctx[0])) {
 		ret = PTR_ERR(dev->alloc_ctx[0]);
 		goto err_res;
 	}
-	dev->alloc_ctx[1] = vb2_dma_contig_init_ctx(dev->mem_dev_r);
+	dev->alloc_ctx[1] = vb2_dma_contig_init_ctx_attrs(dev->mem_dev_r,
+							  &attrs);
 	if (IS_ERR(dev->alloc_ctx[1])) {
 		ret = PTR_ERR(dev->alloc_ctx[1]);
 		goto err_mem_init_ctx_1;
-- 
2.6.0.rc2.230.g3dd15c0




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