Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751893AbdFPFnJ (ORCPT ); Fri, 16 Jun 2017 01:43:09 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:55722 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbdFPFnG (ORCPT ); Fri, 16 Jun 2017 01:43:06 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 1D7F260A4F Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=architt@codeaurora.org Subject: Re: [PATCH 1/7] drm/bridge: Support hotplugging panel-bridge. To: Eric Anholt , dri-devel@lists.freedesktop.org, Andrzej Hajda , Laurent Pinchart , Thierry Reding , Rob Herring , Mark Rutland , devicetree@vger.kernel.org Cc: linux-kernel@vger.kernel.org References: <20170615204130.19255-1-eric@anholt.net> <20170615204130.19255-2-eric@anholt.net> From: Archit Taneja Message-ID: <777ee1b1-e5ce-ea29-8a48-f792354a22d1@codeaurora.org> Date: Fri, 16 Jun 2017 11:13:01 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170615204130.19255-2-eric@anholt.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1656 Lines: 51 On 06/16/2017 02:11 AM, Eric Anholt wrote: > If the panel-bridge is being set up after the drm_mode_config_reset(), > then the connector's state would never get initialized, and we'd > dereference the NULL in the hotplug path. We also need to register > the connector, so that userspace can get at it. > Shouldn't the KMS driver make sure the panel-bridge is set up before drm_mode_config_reset? Is it the case when we're inserting the panel-bridge driver as a module? All the connectors that have been added are registered automatically when drm_dev_register() is called by the KMS driver. Registering a connector in the middle of setting up our driver is prone to race conditions if the userspace decides to use them immediately. Thanks, Archit > Signed-off-by: Eric Anholt > --- > drivers/gpu/drm/bridge/panel.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c > index 67fe19e5a9c6..8ed8a70799c7 100644 > --- a/drivers/gpu/drm/bridge/panel.c > +++ b/drivers/gpu/drm/bridge/panel.c > @@ -82,11 +82,14 @@ static int panel_bridge_attach(struct drm_bridge *bridge) > > drm_mode_connector_attach_encoder(&panel_bridge->connector, > bridge->encoder); > + drm_atomic_helper_connector_reset(&panel_bridge->connector); > > ret = drm_panel_attach(panel_bridge->panel, &panel_bridge->connector); > if (ret < 0) > return ret; > > + drm_connector_register(&panel_bridge->connector); > + > return 0; > } > > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project