linux-kernel - [PATCH v2 9/9] drm/i915: use DMA_ATTR_PERSISTENT

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Date:   Fri,  6 Aug 2021 19:34:23 +0900
From:   David Stevens <stevensd@...omium.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Christoph Hellwig <hch@....de>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        David Stevens <stevensd@...omium.org>
Subject: [PATCH v2 9/9] drm/i915: use DMA_ATTR_PERSISTENT_STREAMING flag

From: David Stevens <stevensd@...omium.org>

Use the new DMA_ATTR_PERSISTENT_STREAMING for long lived dma mappings
which directly handle CPU cache coherency instead of using dma_sync_*.

Signed-off-by: David Stevens <stevensd@...omium.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 4 +++-
 drivers/gpu/drm/i915/i915_gem_gtt.c        | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 616c3a2f1baf..df982cfb4f34 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -48,7 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
 		src = sg_next(src);
 	}
 
-	ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC);
+	ret = dma_map_sgtable(attachment->dev, st, dir,
+			      DMA_ATTR_SKIP_CPU_SYNC |
+			      DMA_ATTR_PERSISTENT_STREAMING);
 	if (ret)
 		goto err_free_sg;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 36489be4896b..f27a849631f7 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -33,7 +33,8 @@ int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
 				     PCI_DMA_BIDIRECTIONAL,
 				     DMA_ATTR_SKIP_CPU_SYNC |
 				     DMA_ATTR_NO_KERNEL_MAPPING |
-				     DMA_ATTR_NO_WARN))
+				     DMA_ATTR_NO_WARN |
+				     DMA_ATTR_PERSISTENT_STREAMING))
 			return 0;
 
 		/*
-- 
2.32.0.605.g8dce9f2422-goog