Re: [PATCH v2 5/6] drm/ttm: stop allocating a dummy resource for pipelined gutting

["Das, Nirmoy" <nirmoy.das@xxxxxxxxxxxxxxx>]

On 1/30/2023 1:06 PM, Matthew Auld wrote:
> From: Christian König <christian.koenig@xxxxxxx>
>
> That should not be necessary any more when drivers should at least be
> able to handle a move without a resource.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Acked-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_util.c | 15 ++-------------
>   1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 7635d7d6b13b..d9d2b0903b22 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -704,30 +704,23 @@ EXPORT_SYMBOL(ttm_bo_move_sync_cleanup);
>    */
>   int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
>   {
> -	static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
>   	struct ttm_buffer_object *ghost;
> -	struct ttm_resource *sys_res;
>   	struct ttm_tt *ttm;
>   	int ret;
>   
> -	ret = ttm_resource_alloc(bo, &sys_mem, &sys_res);
> -	if (ret)
> -		return ret;
> -
>   	/* If already idle, no need for ghost object dance. */
>   	if (dma_resv_test_signaled(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP)) {
>   		if (!bo->ttm) {
>   			/* See comment below about clearing. */
>   			ret = ttm_tt_create(bo, true);
>   			if (ret)
> -				goto error_free_sys_mem;
> +				return ret;
>   		} else {
>   			ttm_tt_unpopulate(bo->bdev, bo->ttm);
>   			if (bo->type == ttm_bo_type_device)
>   				ttm_tt_mark_for_clear(bo->ttm);
>   		}
>   		ttm_resource_free(bo, &bo->resource);
> -		ttm_bo_assign_mem(bo, sys_res);
>   		return 0;
>   	}
>   
> @@ -744,7 +737,7 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
>   	ret = ttm_tt_create(bo, true);
>   	swap(bo->ttm, ttm);
>   	if (ret)
> -		goto error_free_sys_mem;
> +		return ret;
>   
>   	ret = ttm_buffer_object_transfer(bo, &ghost);
>   	if (ret)
> @@ -760,13 +753,9 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
>   	dma_resv_unlock(&ghost->base._resv);
>   	ttm_bo_put(ghost);
>   	bo->ttm = ttm;
> -	ttm_bo_assign_mem(bo, sys_res);
>   	return 0;
>   
>   error_destroy_tt:
>   	ttm_tt_destroy(bo->bdev, ttm);
> -
> -error_free_sys_mem:
> -	ttm_resource_free(bo, &sys_res);
>   	return ret;
>   }