From 791d44122ed291f46e30a4ea593a99ac6ea1fc0c Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 30 Nov 2017 18:07:02 +0000
Subject: drm/i915: Skip CPU synchronisation on dmabuf attachments
Git-commit: cbc1f3cb67b6ec13182117a329b6f03810c03cf6
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
dma-bufs are device coherent, with explicit CPU synchronisation provided
via the begin/end cpu access ioctls. As the coherency of the dma-buf is
explicitly defined to be under user control, flushing any caches on
attach/detach of the dma-buf is additional work that doesn't aide the
user in the slightest.
Suggested-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dongwon Kim <dongwon.kim@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171130180702.29357-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 8 ++++++--
1 file changed, 6 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 372b57ca0efc..7db5a793739d 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);
}
- if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
+ if (!dma_map_sg_attrs(attachment->dev,
+ st->sgl, st->nents, dir,
+ DMA_ATTR_SKIP_CPU_SYNC)) {
ret = -ENOMEM;
goto err_free_sg;
}
@@ -71,7 +73,9 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
{
struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf);
- dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
+ dma_unmap_sg_attrs(attachment->dev,
+ sg->sgl, sg->nents, dir,
+ DMA_ATTR_SKIP_CPU_SYNC);
sg_free_table(sg);
kfree(sg);
--
2.28.0