From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752898AbaBXPHV (ORCPT ); Mon, 24 Feb 2014 10:07:21 -0500 Received: from smtp4.epfl.ch ([128.178.224.219]:38657 "EHLO smtp4.epfl.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752313AbaBXPHT (ORCPT ); Mon, 24 Feb 2014 10:07:19 -0500 Message-ID: <530B6023.5020400@epfl.ch> Date: Mon, 24 Feb 2014 16:07:15 +0100 From: =?ISO-8859-1?Q?Philippe_R=E9tornaz?= Organization: EPFL - LSRO1 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Sachin Kamat CC: Mark Brown , LKML , Liam Girdwood Subject: Re: [PATCH 13/16] regulator: mc13xxx: Use of_get_child_by_name References: <530B4CB6.9010608@epfl.ch> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 24/02/2014 15:51, Sachin Kamat a écrit : > On 24 February 2014 19:14, Philippe Rétornaz > wrote: >> Hi >> >> This patch breaks DT-Enabled kernel run on non-DT board: [ >> 0.822977] Unable to handle kernel NULL pointer dereference at >> virtual address 0000001c (...) [ 0.880320] [] >> (of_get_next_child) from [] >> (of_get_child_by_name+0x38/0x50) [ 0.881449] [] >> (of_get_child_by_name) from [] >> (mc13xxx_get_num_regulators_dt+0x18/0x64) [ 0.882707] >> [] (mc13xxx_get_num_regulators_dt) from [] >> (mc13783_regulator_probe+0x34/0x17c) [ 0.884011] [] >> (mc13783_regulator_probe) from [] >> (platform_drv_probe+0x20/0x54) [ 0.885182] [] >> (platform_drv_probe) from [] >> (driver_probe_device+0x144/0x360) (...) >> >> Because mc13783-regulator do in its probe: static int >> mc13783_regulator_probe(struct platform_device *pdev) { (...) int >> i, num_regulators; >> >> num_regulators = mc13xxx_get_num_regulators_dt(pdev); if >> (num_regulators <= 0 && pdata) num_regulators = >> pdata->num_regulators >> >> >> and mc13xxx_get_num_regulators_dt() do, before your patch: >> >> parent = of_find_node_by_name(pdev->dev.parent->of_node, >> "regulators"); if (!parent) return -ENODEV; >> >> of_find_node_by_name will return NULL if the node passed is NULL >> and the DT is non-existant. >> >> But, with your change we use this: parent = >> of_get_child_by_name(pdev->dev.parent->of_node, "regulators"); >> >> Which will OOPS as it does not expect to have a NULL node passed as >> argument. >> >> So please revert this patch. > > Sorry for the issue caused due to this patch. I would prefer to try > to have this fixed before reverting. Can you please try with below > change and let me know if it works: > > parent = of_get_child_by_name(pdev->dev->of_node, "regulators"); > You meant pdev->dev.of_node here I guess ? This still OOPS as the board is not booting with DT, so all of_node are NULL. > Also, how about adding NULL check to see it the node exists at all? > Could be an option. BTW, mc13xxx_parse_regulators_dt() has the same problem. Regards, Philippe