Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752867Ab1BAU7O (ORCPT ); Tue, 1 Feb 2011 15:59:14 -0500 Received: from wolverine01.qualcomm.com ([199.106.114.254]:22849 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752737Ab1BAU7M (ORCPT ); Tue, 1 Feb 2011 15:59:12 -0500 X-IronPort-AV: E=McAfee;i="5400,1158,6244"; a="72828978" Message-ID: <4D48741F.8060006@codeaurora.org> Date: Tue, 01 Feb 2011 12:59:11 -0800 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: Russell King - ARM Linux CC: =?ISO-8859-1?Q?Uwe_Kleine-K=F6nig?= , Nicolas Pitre , Lorenzo Pieralisi , Saravana Kannan , linux-sh@vger.kernel.org, Ben Herrenschmidt , Sascha Hauer , Paul Mundt , linux-kernel@vger.kernel.org, Dima Zavin , Ben Dooks , Vincent Guittot , Jeremy Kerr , linux-arm-kernel@lists.infradead.org Subject: Re: Locking in the clk API, part 2: clk_prepare/clk_unprepare References: <201102011711.31258.jeremy.kerr@canonical.com> <20110201105449.GY1147@pengutronix.de> <20110201131512.GH31216@n2100.arm.linux.org.uk> <20110201141837.GA1147@pengutronix.de> <20110201143932.GK31216@n2100.arm.linux.org.uk> <20110201151846.GD1147@pengutronix.de> <20110201152458.GP31216@n2100.arm.linux.org.uk> In-Reply-To: <20110201152458.GP31216@n2100.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 997 Lines: 34 On 02/01/2011 07:24 AM, Russell King - ARM Linux wrote: > > I'd also be tempted at this stage to build-in a no-op dummy clock, > that being the NULL clk: > > int clk_prepare(struct clk *clk) > { > int ret = 0; > > if (clk) { > mutex_lock(&clk->mutex); > if (clk->prepared == 0) > ret = clk->ops->prepare(clk); > if (ret == 0) > clk->prepared++; > mutex_unlock(&clk->mutex); > } > > return ret; > } I'm afraid this will hide enable/disable imbalances on some targets and then expose them on others. Maybe its not a big problem though since this also elegantly handles the root(s) of the tree. -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/