drm: remove prime sg_table caching

That is now done by the DMA-buf helpers instead.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.kernel.org/patch/10943055/

drivers/gpu/drm/drm_prime.c

@@ -86,11 +86,6 @@ struct drm_prime_member {
 	struct rb_node handle_rb;
 };
 
-struct drm_prime_attachment {
-	struct sg_table *sgt;
-	enum dma_data_direction dir;
-};
-
 static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
 				    struct dma_buf *dma_buf, uint32_t handle)
 {
@@ -188,25 +183,16 @@ static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpri
  * @dma_buf: buffer to attach device to
  * @attach: buffer attachment data
  *
- * Allocates &drm_prime_attachment and calls &drm_driver.gem_prime_pin for
- * device specific attachment. This can be used as the &dma_buf_ops.attach
- * callback.
+ * Calls &drm_driver.gem_prime_pin for device specific handling. This can be
+ * used as the &dma_buf_ops.attach callback.
  *
  * Returns 0 on success, negative error code on failure.
  */
 int drm_gem_map_attach(struct dma_buf *dma_buf,
 		       struct dma_buf_attachment *attach)
 {
-	struct drm_prime_attachment *prime_attach;
 	struct drm_gem_object *obj = dma_buf->priv;
 
-	prime_attach = kzalloc(sizeof(*prime_attach), GFP_KERNEL);
-	if (!prime_attach)
-		return -ENOMEM;
-
-	prime_attach->dir = DMA_NONE;
-	attach->priv = prime_attach;
-
 	return drm_gem_pin(obj);
 }
 EXPORT_SYMBOL(drm_gem_map_attach);
@@ -222,26 +208,8 @@ EXPORT_SYMBOL(drm_gem_map_attach);
 void drm_gem_map_detach(struct dma_buf *dma_buf,
 			struct dma_buf_attachment *attach)
 {
-	struct drm_prime_attachment *prime_attach = attach->priv;
 	struct drm_gem_object *obj = dma_buf->priv;
 
-	if (prime_attach) {
-		struct sg_table *sgt = prime_attach->sgt;
-
-		if (sgt) {
-			if (prime_attach->dir != DMA_NONE)
-				dma_unmap_sg_attrs(attach->dev, sgt->sgl,
-						   sgt->nents,
-						   prime_attach->dir,
-						   DMA_ATTR_SKIP_CPU_SYNC);
-			sg_free_table(sgt);
-		}
-
-		kfree(sgt);
-		kfree(prime_attach);
-		attach->priv = NULL;
-	}
-
 	drm_gem_unpin(obj);
 }
 EXPORT_SYMBOL(drm_gem_map_detach);
@@ -286,39 +254,22 @@ void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpr
 struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 				     enum dma_data_direction dir)
 {
-	struct drm_prime_attachment *prime_attach = attach->priv;
 	struct drm_gem_object *obj = attach->dmabuf->priv;
 	struct sg_table *sgt;
 
-	if (WARN_ON(dir == DMA_NONE || !prime_attach))
+	if (WARN_ON(dir == DMA_NONE))
 		return ERR_PTR(-EINVAL);
 
-	/* return the cached mapping when possible */
-	if (prime_attach->dir == dir)
-		return prime_attach->sgt;
-
-	/*
-	 * two mappings with different directions for the same attachment are
-	 * not allowed
-	 */
-	if (WARN_ON(prime_attach->dir != DMA_NONE))
-		return ERR_PTR(-EBUSY);
-
 	if (obj->funcs)
 		sgt = obj->funcs->get_sg_table(obj);
 	else
 		sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
 
-	if (!IS_ERR(sgt)) {
 	if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
 			      DMA_ATTR_SKIP_CPU_SYNC)) {
 		sg_free_table(sgt);
 		kfree(sgt);
 		sgt = ERR_PTR(-ENOMEM);
-		} else {
-			prime_attach->sgt = sgt;
-			prime_attach->dir = dir;
-		}
 	}
 
 	return sgt;
@@ -331,14 +282,19 @@ EXPORT_SYMBOL(drm_gem_map_dma_buf);
  * @sgt: scatterlist info of the buffer to unmap
  * @dir: direction of DMA transfer
  *
- * Not implemented. The unmap is done at drm_gem_map_detach().  This can be
- * used as the &dma_buf_ops.unmap_dma_buf callback.
+ * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
  */
 void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 			   struct sg_table *sgt,
 			   enum dma_data_direction dir)
 {
-	/* nothing to be done here */
+	if (!sgt)
+		return;
+
+	dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
+			   DMA_ATTR_SKIP_CPU_SYNC);
+	sg_free_table(sgt);
+	kfree(sgt);
 }
 EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
 
@@ -452,6 +408,7 @@ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
 
 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
+	.cache_sgt_mapping = true,
 	.attach = drm_gem_map_attach,
 	.detach = drm_gem_map_detach,
 	.map_dma_buf = drm_gem_map_dma_buf,