drm/nouveau/gr: disable fifo access and idle before suspend ctx unload

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nv20_graph.c b/drivers/gpu/drm/nouveau/nv20_graph.c
index a54b7d9..183e375 100644
--- a/drivers/gpu/drm/nouveau/nv20_graph.c
+++ b/drivers/gpu/drm/nouveau/nv20_graph.c
@@ -656,6 +656,11 @@
 int
 nv20_graph_fini(struct drm_device *dev, int engine, bool suspend)
 {
+	nv_mask(dev, NV04_PGRAPH_FIFO, 0x00000001, 0x00000000);
+	if (!nv_wait(dev, NV04_PGRAPH_STATUS, ~0, 0) && suspend) {
+		nv_mask(dev, NV04_PGRAPH_FIFO, 0x00000001, 0x00000001);
+		return -EBUSY;
+	}
 	nv20_graph_unload_context(dev);
 	nv_wr32(dev, NV03_PGRAPH_INTR_EN, 0x00000000);
 	return 0;