Revert "Revert "drm/panfrost: Use drm_gem_map_offset()""

This reverts commit be855382.

Mandatory review was missing from this patch.
Acked-by: NMaxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: NSean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190807142101.251400-3-sean@poorly.run

drivers/gpu/drm/panfrost/panfrost_drv.c

@@ -291,26 +291,14 @@ static int panfrost_ioctl_mmap_bo(struct drm_device *dev, void *data,
 		      struct drm_file *file_priv)
 {
 	struct drm_panfrost_mmap_bo *args = data;
-	struct drm_gem_object *gem_obj;
-	int ret;
 
 	if (args->flags != 0) {
 		DRM_INFO("unknown mmap_bo flags: %d\n", args->flags);
 		return -EINVAL;
 	}
 
-	gem_obj = drm_gem_object_lookup(file_priv, args->handle);
-	if (!gem_obj) {
-		DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
-		return -ENOENT;
-	}
-
-	ret = drm_gem_create_mmap_offset(gem_obj);
-	if (ret == 0)
-		args->offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
-	drm_gem_object_put_unlocked(gem_obj);
-
-	return ret;
+	return drm_gem_map_offset(file_priv, dev, args->handle,
+				       &args->offset);
 }
 
 static int panfrost_ioctl_get_bo_offset(struct drm_device *dev, void *data,