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Subject[PATCH 11/12] drm/amdgpu: add DMA-buf pin/unpin implementation
Date
Pin and unpin the DMA-buf exported BOs only on demand and invalidate all
DMA-buf mappings when the underlying BO moves.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 5 ++
drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 73 ++++++++++++++++++++--
2 files changed, 72 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index ec9e45004bff..fdb98eb562db 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -31,6 +31,7 @@
*/
#include <linux/list.h>
#include <linux/slab.h>
+#include <linux/dma-buf.h>
#include <drm/drmP.h>
#include <drm/amdgpu_drm.h>
#include <drm/drm_cache.h>
@@ -1192,6 +1193,10 @@ void amdgpu_bo_move_notify(struct ttm_buffer_object *bo,

amdgpu_bo_kunmap(abo);

+ if (abo->gem_base.dma_buf && !abo->gem_base.import_attach &&
+ bo->mem.mem_type != TTM_PL_SYSTEM)
+ dma_buf_invalidate_mappings(abo->gem_base.dma_buf);
+
/* remember the eviction */
if (evict)
atomic64_inc(&adev->num_evictions);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
index 56e2a606b9a1..40cd89271b20 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
@@ -209,6 +209,61 @@ __reservation_object_make_exclusive(struct reservation_object *obj)
return -ENOMEM;
}

+/**
+ * amdgpu_gem_pin_dma_buf - &dma_buf_ops.pin_dma_buf implementation
+ *
+ * @dma_buf: DMA-buf to pin in memory
+ *
+ * Pin the BO which is backing the DMA-buf so that it can't move any more.
+ */
+static int amdgpu_gem_pin_dma_buf(struct dma_buf *dma_buf)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+ struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+ /* pin buffer into GTT */
+ return amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
+}
+
+/**
+ * amdgpu_gem_unpin_dma_buf - &dma_buf_ops.unpin_dma_buf implementation
+ *
+ * @dma_buf: DMA-buf to unpin
+ *
+ * Unpin a previously pinned BO to make it movable again.
+ */
+static void amdgpu_gem_unpin_dma_buf(struct dma_buf *dma_buf)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+ struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+ amdgpu_bo_unpin(bo);
+}
+
+/**
+ * amdgpu_gem_dma_buf_attach - &dma_buf_ops.attach implementation
+ *
+ * @dma_buf: DMA-buf we attach to
+ * @attach: DMA-buf attachment
+ *
+ * Returns:
+ * Always zero for success.
+ */
+static int amdgpu_gem_dma_buf_attach(struct dma_buf *dma_buf,
+ struct dma_buf_attachment *attach)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+ struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+ /* Make sure the buffer is pinned when userspace didn't set GTT as
+ * preferred domain. This avoid ping/pong situations with scan out BOs.
+ */
+ if (!(bo->preferred_domains & AMDGPU_GEM_DOMAIN_GTT))
+ attach->invalidate = NULL;
+
+ return 0;
+}
+
/**
* amdgpu_gem_map_dma_buf - &dma_buf_ops.map_dma_buf implementation
* @attach: DMA-buf attachment
@@ -247,10 +302,15 @@ amdgpu_gem_map_dma_buf(struct dma_buf_attachment *attach,
return ERR_PTR(r);
}

- /* pin buffer into GTT */
- r = amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
- if (r)
- return ERR_PTR(r);
+ if (attach->invalidate) {
+ /* move buffer into GTT */
+ struct ttm_operation_ctx ctx = { false, false };
+
+ amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);
+ r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
+ if (r)
+ return ERR_PTR(r);
+ }

sgt = drm_prime_pages_to_sg(bo->tbo.ttm->pages, bo->tbo.num_pages);
if (IS_ERR(sgt))
@@ -289,8 +349,6 @@ static void amdgpu_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);

- amdgpu_bo_unpin(bo);
-
if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
bo->prime_shared_count--;

@@ -357,6 +415,9 @@ static int amdgpu_gem_begin_cpu_access(struct dma_buf *dma_buf,

const struct dma_buf_ops amdgpu_dmabuf_ops = {
.dynamic_sgt_mapping = true,
+ .attach = amdgpu_gem_dma_buf_attach,
+ .pin = amdgpu_gem_pin_dma_buf,
+ .unpin = amdgpu_gem_unpin_dma_buf,
.map_dma_buf = amdgpu_gem_map_dma_buf,
.unmap_dma_buf = amdgpu_gem_unmap_dma_buf,
.release = drm_gem_dmabuf_release,
--
2.17.1
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