From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755699Ab2GEKYU (ORCPT ); Thu, 5 Jul 2012 06:24:20 -0400 Received: from va3ehsobe005.messaging.microsoft.com ([216.32.180.31]:36293 "EHLO va3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753476Ab2GEKYS (ORCPT ); Thu, 5 Jul 2012 06:24:18 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -2 X-BigFish: VS-2(zz98dI1432Izz1202hzzz2dh2a8h668h839h944hd25hf0ah107ah) Date: Thu, 5 Jul 2012 18:25:29 +0800 From: Zhao Chenhui To: Tabi Timur-B04825 CC: Zhao Chenhui-B35336 , "linuxppc-dev@lists.ozlabs.org" , Wood Scott-B07421 , "galak@kernel.crashing.org" , "linux-kernel@vger.kernel.org" , Li Yang-R58472 , Subject: Re: [PATCH v7 1/5] powerpc/85xx: implement hardware timebase sync Message-ID: <20120705102529.GA7982@localhost.localdomain> References: <1341310879-5468-1-git-send-email-chenhui.zhao@freescale.com> <20120704031426.GA6133@localhost.localdomain> <4FF3B5B6.8090400@freescale.com> <20120704034545.GA6196@localhost.localdomain> <4FF45F19.2080607@freescale.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4FF45F19.2080607@freescale.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: freescale.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 04, 2012 at 10:19:54AM -0500, Tabi Timur-B04825 wrote: > Zhao Chenhui wrote: > > On Tue, Jul 03, 2012 at 10:17:12PM -0500, Tabi Timur-B04825 wrote: > >> Zhao Chenhui wrote: > >>> If the guts variable is NULL, it indicates there is error in dts or kernel. > >>> We should fix the error, rather than ignore it. > >> > >> And that's why there's a warning message. Crashing the kernel is not > >> going to fix anything. > >> > > > > This error likely crashes the kenel somewhere. > > Can you test this, please? > > The point I'm trying to make is that it's wrong to intentionally halt the > kernel unless you're sure that it's the best option. A missing device > tree node is supposed to only disable a given feature, not break everything. > I think there is some misunderstanding here. np = of_find_matching_node(NULL, mpc85xx_smp_guts_ids); if (np) { guts = of_iomap(np, 0); of_node_put(np); if (!guts) { pr_err("%s: Could not map guts node address\n", __func__); return; } smp_85xx_ops.give_timebase = mpc85xx_give_timebase; smp_85xx_ops.take_timebase = mpc85xx_take_timebase; } If the guts node is missing, this code snippet will be skipped. If the guts node is existed, the return value of of_iomap(), namely guts, will be tested. If it is NULL, it shows that there is error in dts, or the ioremap() in of_iomap() failed. I think these errors are fatal errors, so I print an error info and return. -Chenhui