drm/amdgpu: Improve documentation of bo_ptr in amdgpu_bo_create_kernel

and amdgpu_bo_create_reserved.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_object.c

@@ -175,13 +175,15 @@ void amdgpu_ttm_placement_from_domain(struct amdgpu_bo *abo, u32 domain)
  * @size: size for the new BO
  * @align: alignment for the new BO
  * @domain: where to place it
- * @bo_ptr: resulting BO
+ * @bo_ptr: used to initialize BOs in structures
  * @gpu_addr: GPU addr of the pinned BO
  * @cpu_addr: optional CPU address mapping
  *
  * Allocates and pins a BO for kernel internal use, and returns it still
  * reserved.
  *
+ * Note: For bo_ptr new BO is only created if bo_ptr points to NULL.
+ *
  * Returns 0 on success, negative error code otherwise.
  */
 int amdgpu_bo_create_reserved(struct amdgpu_device *adev,
@@ -244,12 +246,14 @@ int amdgpu_bo_create_reserved(struct amdgpu_device *adev,
  * @size: size for the new BO
  * @align: alignment for the new BO
  * @domain: where to place it
- * @bo_ptr: resulting BO
+ * @bo_ptr:  used to initialize BOs in structures
  * @gpu_addr: GPU addr of the pinned BO
  * @cpu_addr: optional CPU address mapping
  *
  * Allocates and pins a BO for kernel internal use.
  *
+ * Note: For bo_ptr new BO is only created if bo_ptr points to NULL.
+ *
  * Returns 0 on success, negative error code otherwise.
  */
 int amdgpu_bo_create_kernel(struct amdgpu_device *adev,