nouveau: explicitly wait on the fence in nouveau_bo_move_m2mf

It is a bit unlcear to us why that's helping, but it does and unbreaks
suspend/resume on a lot of GPUs without any known drawbacks.

Cc: [email protected] # v5.15+
Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/156
Signed-off-by: Karol Herbst <[email protected]>
Reviewed-by: Lyude Paul <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: karolherbst

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -820,6 +820,15 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict,
 		if (ret == 0) {
 			ret = nouveau_fence_new(chan, false, &fence);
 			if (ret == 0) {
+				/* TODO: figure out a better solution here
+				 *
+				 * wait on the fence here explicitly as going through
+				 * ttm_bo_move_accel_cleanup somehow doesn't seem to do it.
+				 *
+				 * Without this the operation can timeout and we'll fallback to a
+				 * software copy, which might take several minutes to finish.
+				 */
+				nouveau_fence_wait(fence, false, false);
 				ret = ttm_bo_move_accel_cleanup(bo,
 								&fence->base,
 								evict, false,