Or users can just spam the log all they want.
Issue introduced in
commit 
9a8f0a1290993c86c4e35756a2624bfe461f9036
Author: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Date:   Fri Feb 27 11:15:24 2015 +0000
    drm/i915/skl: Allow Y (and Yf) frame buffer creation
References: https://bugs.freedesktop.org/show_bug.cgi?id=89628
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
        case I915_FORMAT_MOD_X_TILED:
                break;
        default:
-               DRM_ERROR("Unsupported fb modifier 0x%llx!\n",
-                               mode_cmd->modifier[0]);
+               DRM_DEBUG("Unsupported fb modifier 0x%llx!\n",
+                         mode_cmd->modifier[0]);
                return -EINVAL;
        }