drm/nouveau/engine: add HAL for engine-specific rc reset procedure

Will be used to improve gr reset on GF100 and newer.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/core/engine.h

@@ -21,6 +21,7 @@ struct nvkm_engine_func {
 	int (*info)(struct nvkm_engine *, u64 mthd, u64 *data);
 	int (*init)(struct nvkm_engine *);
 	int (*fini)(struct nvkm_engine *, bool suspend);
+	int (*reset)(struct nvkm_engine *);
 	void (*intr)(struct nvkm_engine *);
 	void (*tile)(struct nvkm_engine *, int region, struct nvkm_fb_tile *);
 	bool (*chsw_load)(struct nvkm_engine *);
@@ -48,6 +49,7 @@ int nvkm_engine_new_(const struct nvkm_engine_func *, struct nvkm_device *,
 
 struct nvkm_engine *nvkm_engine_ref(struct nvkm_engine *);
 void nvkm_engine_unref(struct nvkm_engine **);
+int nvkm_engine_reset(struct nvkm_engine *);
 void nvkm_engine_tile(struct nvkm_engine *, int region);
 bool nvkm_engine_chsw_load(struct nvkm_engine *);
 #endif

drivers/gpu/drm/nouveau/nvkm/core/engine.c

@@ -35,6 +35,16 @@ nvkm_engine_chsw_load(struct nvkm_engine *engine)
 	return false;
 }
 
+int
+nvkm_engine_reset(struct nvkm_engine *engine)
+{
+	if (engine->func->reset)
+		return engine->func->reset(engine);
+
+	nvkm_subdev_fini(&engine->subdev, false);
+	return nvkm_subdev_init(&engine->subdev);
+}
+
 void
 nvkm_engine_unref(struct nvkm_engine **pengine)
 {

drivers/gpu/drm/nouveau/nvkm/engine/fifo/runl.c

@@ -113,8 +113,8 @@ nvkm_runl_rc(struct nvkm_runl *runl)
 		}
 
 		ENGN_DEBUG(engn, "resetting...");
-		nvkm_subdev_fini(&engn->engine->subdev, false);
-		WARN_ON(nvkm_subdev_init(&engn->engine->subdev));
+		/*TODO: can we do something less of a potential catastrophe on failure? */
+		WARN_ON(nvkm_engine_reset(engn->engine));
 	}
 
 	/* Submit runlist update, and clear any remaining exception state. */