From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755849AbbA2QGW (ORCPT ); Thu, 29 Jan 2015 11:06:22 -0500 Received: from pandora.arm.linux.org.uk ([78.32.30.218]:34491 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752375AbbA2QGU (ORCPT ); Thu, 29 Jan 2015 11:06:20 -0500 Date: Thu, 29 Jan 2015 16:05:53 +0000 From: Russell King - ARM Linux To: Peter Hurley , Thierry Reding Cc: Varka Bhadram , Chunyan Zhang , gregkh@linuxfoundation.org, mark.rutland@arm.com, gnomes@lxorguk.ukuu.org.uk, heiko@sntech.de, andrew@lunn.ch, jslaby@suse.cz, lanqing.liu@spreadtrum.com, pawel.moll@arm.com, zhang.lyra@gmail.com, zhizhou.zhang@spreadtrum.com, geng.ren@spreadtrum.com, antonynpavlov@gmail.com, linux-serial@vger.kernel.org, grant.likely@linaro.org, orsonzhai@gmail.com, florian.vaussard@epfl.ch, devicetree@vger.kernel.org, jason@lakedaemon.net, arnd@arndb.de, ijc+devicetree@hellion.org.uk, hytszk@gmail.com, robh+dt@kernel.org, wei.qiao@spreadtrum.com, linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, galak@codeaurora.org, shawn.guo@linaro.org Subject: Re: [PATCH v10 2/2] tty/serial: Add Spreadtrum sc9836-uart driver support Message-ID: <20150129160553.GC26493@n2100.arm.linux.org.uk> References: <1422443324-25082-1-git-send-email-chunyan.zhang@spreadtrum.com> <1422443324-25082-3-git-send-email-chunyan.zhang@spreadtrum.com> <54CA5128.8050500@gmail.com> <54CA568E.6080306@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54CA568E.6080306@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 29, 2015 at 10:49:34AM -0500, Peter Hurley wrote: > Hi Varka, > > On 01/29/2015 10:26 AM, Varka Bhadram wrote: > > This check is not required. It will be done by devm_ioremap_resource() > > I disagree. devm_ioremap_resource() interprets the NULL resource as > a bad parameter and returns -EINVAL which is then forwarded as the > return value from the probe. > > -ENODEV is the correct return value from the probe if the expected > resource is not available (either because it doesn't exist or was already > claimed by another driver). (Adding Thierry as the author of this function.) I believe devm_ioremap_resource() was explicitly designed to remove such error handling from drivers, and to give drivers a unified error response to such things as missing resources. See the comments for this function in lib/devres.c. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.