[PATCH 5.10 136/143] nouveau: explicitly wait on the fence in nouveau_bo_move_m2mf

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Karol Herbst <kherbst@redhat.com>

commit 6b04ce966a738ecdd9294c9593e48513c0dc90aa upstream.

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: stable@vger.kernel.org # v5.15+
Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/156
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220819200928.401416-1-kherbst@redhat.com
Cc: Salvatore Bonaccorso <carnil@debian.org>
Cc: Computer Enthusiastic <computer.enthusiastic@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/nouveau/nouveau_bo.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -823,6 +823,15 @@ nouveau_bo_move_m2mf(struct ttm_buffer_o
 		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,