diff --git a/sys/arch/arm/rockchip/rk_drm.c b/sys/arch/arm/rockchip/rk_drm.c
index 2d57727f1b77..5e2e212f9fee 100644
--- a/sys/arch/arm/rockchip/rk_drm.c
+++ b/sys/arch/arm/rockchip/rk_drm.c
@@ -235,16 +235,8 @@ rk_drm_fb_create(struct drm_device *ddev, struct drm_file *file,
 		return NULL;
 
 	fb = kmem_zalloc(sizeof(*fb), KM_SLEEP);
+	drm_helper_mode_fill_fb_struct(ddev, &fb->base, cmd);
 	fb->obj = to_drm_gem_cma_obj(gem_obj);
-	fb->base.pitches[0] = cmd->pitches[0];
-	fb->base.pitches[1] = cmd->pitches[1];
-	fb->base.pitches[2] = cmd->pitches[2];
-	fb->base.offsets[0] = cmd->offsets[0];
-	fb->base.offsets[1] = cmd->offsets[2];
-	fb->base.offsets[2] = cmd->offsets[1];
-	fb->base.width = cmd->width;
-	fb->base.height = cmd->height;
-	fb->base.format = drm_format_info(cmd->pixel_format);
 
 	error = drm_framebuffer_init(ddev, &fb->base, &rk_drm_framebuffer_funcs);
 	if (error != 0)
@@ -296,10 +288,14 @@ rk_drm_fb_probe(struct drm_fb_helper *helper, struct drm_fb_helper_surface_size
 		return -ENOMEM;
 	}
 
+	/* similar to drm_helper_mode_fill_fb_struct(), but we have no cmd */
 	fb->pitches[0] = pitch;
 	fb->offsets[0] = 0;
 	fb->width = width;
 	fb->height = height;
+	fb->dev = ddev;
+	fb->modifier = 0;
+	fb->flags = 0;
 #ifdef __ARM_BIG_ENDIAN
 	fb->format = drm_format_info(DRM_FORMAT_BGRX8888);
 #else
diff --git a/sys/arch/arm/rockchip/rk_fb.c b/sys/arch/arm/rockchip/rk_fb.c
index b165daf2e89f..d13fddeecf7b 100644
--- a/sys/arch/arm/rockchip/rk_fb.c
+++ b/sys/arch/arm/rockchip/rk_fb.c
@@ -102,7 +102,9 @@ rk_fb_attach(device_t parent, device_t self, void *aux)
 		.da_params = &rkfb_drmfb_params,
 	};
 
+	mutex_unlock(&sfa->sfa_fb_helper->lock); /* XXX */
 	error = drmfb_attach(&sc->sc_drmfb, &da);
+	mutex_lock(&sfa->sfa_fb_helper->lock); /* XXX */
 	if (error) {
 		aprint_error_dev(self, "failed to attach drmfb: %d\n", error);
 		return;