From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Pitre Subject: Re: [RFC PATCH v3 2/2] drivers: mfd: vexpress: add Serial Power Controller (SPC) support Date: Thu, 13 Jun 2013 20:21:29 -0400 (EDT) Message-ID: References: <1370512763-32200-1-git-send-email-lorenzo.pieralisi@arm.com> <1370512763-32200-3-git-send-email-lorenzo.pieralisi@arm.com> <20130613225233.GB22310@quad.lixom.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130613225233.GB22310-O5ziIzlqnXUVNXGz7ipsyg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Olof Johansson Cc: Jon Medhurst , Lorenzo Pieralisi , Samuel Ortiz , Pawel Moll , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Amit Kucheria , Achin Gupta , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Thu, 13 Jun 2013, Olof Johansson wrote: > > + u32 status = readl_relaxed(info->baseaddr + PWC_STATUS); > > Why readl_relaxed() here? Can't you use a normal readl()? Unfortunately, on ARM readl_relaxed() _is_ the normal readl() because the actual readl() may have side effects. See commit 79f64dbf68c8. Nicolas