The GEM CMA helper allocates GEM objects with dma_alloc_writecombine(),
so the objects are cache coherent, and the exporter methods for these
objects can skip cache sync.
To accomplish this a dma atrribute is added to drm_gem_object,
and is used with dma_map_sg_attrs/dma_unmap_sg_attrs in
drm_gem_map_dma_buf/drm_gem_map_detach. GEM CMA sets the attribute
to DMA_ATTR_SKIP_CPU_SYNC when the object is allocated in
drm_gem_cma_create().
Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
---
drivers/gpu/drm/drm_gem.c | 1 +
drivers/gpu/drm/drm_gem_cma_helper.c | 2 ++
drivers/gpu/drm/drm_prime.c | 7 ++++---
include/drm/drm_gem.h | 5 +++++
4 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 16a1647..f7f4531 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -169,6 +169,7 @@ void drm_gem_private_object_init(struct drm_device *dev,
obj->handle_count = 0;
obj->size = size;
drm_vma_node_reset(&obj->vma_node);
+ init_dma_attrs(&obj->dma_attrs);
}
EXPORT_SYMBOL(drm_gem_private_object_init);
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index bd75f30..73c949a 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -75,6 +75,8 @@ __drm_gem_cma_create(struct drm_device *drm, size_t size)
goto error;
}
+ dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &gem_obj->dma_attrs);
+
return cma_obj;
error:
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 9f935f5..9eaa8d3 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -153,8 +153,8 @@ static void drm_gem_map_detach(struct dma_buf *dma_buf,
sgt = prime_attach->sgt;
if (sgt) {
if (prime_attach->dir != DMA_NONE)
- dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
- prime_attach->dir);
+ dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents,
+ prime_attach->dir, &obj->dma_attrs);
sg_free_table(sgt);
}
@@ -201,7 +201,8 @@ static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
if (!IS_ERR(sgt)) {
- if (!dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir)) {
+ if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents,
+ dir, &obj->dma_attrs)) {
sg_free_table(sgt);
kfree(sgt);
sgt = ERR_PTR(-ENOMEM);
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 7a592d7..f5546bf 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -104,6 +104,11 @@ struct drm_gem_object {
struct dma_buf *dma_buf;
/**
+ * dma_attrs - DMA attributes for this GEM object
+ */
+ struct dma_attrs dma_attrs;
+
+ /**
* import_attach - dma buf attachment backing this object
*
* Any foreign dma_buf imported as a gem object has this set to the
--
1.9.1
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