drm/ttm: add optional bind/unbind via driver.

I want to remove the backend funcs
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200907204630.1406528-3-airlied@gmail.com

drivers/gpu/drm/ttm/ttm_tt.c

@@ -222,7 +222,10 @@ void ttm_tt_destroy(struct ttm_bo_device *bdev, struct ttm_tt *ttm)
 		fput(ttm->swap_storage);
 
 	ttm->swap_storage = NULL;
-	ttm->func->destroy(bdev, ttm);
+	if (bdev->driver->ttm_tt_destroy)
+		bdev->driver->ttm_tt_destroy(bdev, ttm);
+	else
+		ttm->func->destroy(bdev, ttm);
 }
 
 static void ttm_tt_init_fields(struct ttm_tt *ttm,
@@ -310,7 +313,10 @@ EXPORT_SYMBOL(ttm_dma_tt_fini);
 void ttm_tt_unbind(struct ttm_bo_device *bdev, struct ttm_tt *ttm)
 {
 	if (ttm->state == tt_bound) {
-		ttm->func->unbind(bdev, ttm);
+		if (bdev->driver->ttm_tt_unbind)
+			bdev->driver->ttm_tt_unbind(bdev, ttm);
+		else
+			ttm->func->unbind(bdev, ttm);
 		ttm->state = tt_unbound;
 	}
 }
@@ -331,7 +337,10 @@ int ttm_tt_bind(struct ttm_bo_device *bdev,
 	if (ret)
 		return ret;
 
-	ret = ttm->func->bind(bdev, ttm, bo_mem);
+	if (bdev->driver->ttm_tt_bind)
+		ret = bdev->driver->ttm_tt_bind(bdev, ttm, bo_mem);
+	else
+		ret = ttm->func->bind(bdev, ttm, bo_mem);
 	if (unlikely(ret != 0))
 		return ret;
 

include/drm/ttm/ttm_bo_driver.h

@@ -90,6 +90,42 @@ struct ttm_bo_driver {
 	 */
 	void (*ttm_tt_unpopulate)(struct ttm_bo_device *bdev, struct ttm_tt *ttm);
 
+	/**
+	 * ttm_tt_bind
+	 *
+	 * @bdev: Pointer to a ttm device
+	 * @ttm: Pointer to a struct ttm_tt.
+	 * @bo_mem: Pointer to a struct ttm_resource describing the
+	 * memory type and location for binding.
+	 *
+	 * Bind the backend pages into the aperture in the location
+	 * indicated by @bo_mem. This function should be able to handle
+	 * differences between aperture and system page sizes.
+	 */
+	int (*ttm_tt_bind)(struct ttm_bo_device *bdev, struct ttm_tt *ttm, struct ttm_resource *bo_mem);
+
+	/**
+	 * ttm_tt_unbind
+	 *
+	 * @bdev: Pointer to a ttm device
+	 * @ttm: Pointer to a struct ttm_tt.
+	 *
+	 * Unbind previously bound backend pages. This function should be
+	 * able to handle differences between aperture and system page sizes.
+	 */
+	void (*ttm_tt_unbind)(struct ttm_bo_device *bdev, struct ttm_tt *ttm);
+
+	/**
+	 * ttm_tt_destroy
+	 *
+	 * @bdev: Pointer to a ttm device
+	 * @ttm: Pointer to a struct ttm_tt.
+	 *
+	 * Destroy the backend. This will be call back from ttm_tt_destroy so
+	 * don't call ttm_tt_destroy from the callback or infinite loop.
+	 */
+	void (*ttm_tt_destroy)(struct ttm_bo_device *bdev, struct ttm_tt *ttm);
+
 	/**
 	 * struct ttm_bo_driver member eviction_valuable
 	 *