From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND Date: Mon, 09 Mar 2015 15:30:01 +0100 Message-ID: <1592385.fqRVVyPSPE@vostro.rjw.lan> References: <1425287898-15093-6-git-send-email-boris.brezillon@free-electrons.com> <1615214.0rkGfM1gZL@vostro.rjw.lan> <20150309075546.GY3989@piout.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from v094114.home.net.pl ([79.96.170.134]:55938 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753685AbbCIOGU (ORCPT ); Mon, 9 Mar 2015 10:06:20 -0400 In-Reply-To: <20150309075546.GY3989@piout.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Alexandre Belloni Cc: Pavel Machek , Sylvain Rochet , Peter Zijlstra , Mark Rutland , Boris Brezillon , Alessandro Zummo , Mike Turquette , Jason Cooper , "rtc-linux@googlegroups.com" , Len Brown , Greg Kroah-Hartman , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Nicolas Ferre , Wim Van Sebroeck , "linux-serial@vger.kernel.org" , Jean-Christophe Plagniol-Villard , Thomas Gleixner , Jiri Slaby , linux-arm-kernel@lists.infradead.org On Monday, March 09, 2015 08:55:46 AM Alexandre Belloni wrote: > Hi, > > On 08/03/2015 at 02:12:53 +0100, Rafael J. Wysocki wrote : > > > > I think you misunderstood, that is exactly the expected behaviour. This > > > > is hardware defined. Once the watchdog is started, nobody can stop it. > > > > Trying to change the mode register will result in a reset of the > > > > SoC. > > > > > > Well, it boils down to "what is stronger". Desire to suspend the > > > system, or desire to reboot the system. > > > > > > It is "echo mem > state", not "echo reboot > state". > > > > > > > It is documented in the datasheet and any user wanting another behaviour > > > > is out of luck. > > > > > > Actaully, your platform should just refuse to enter suspend-to-RAM > > > when hw watchdog is enabled. > > > > Quite likely, depending on how exactly the suspend is implemented. > > > > We've had absolutely zero complain on that. It is quite clear in the > datasheet that failing to refresh the watchdog once started will lead to > a reset and that it is impossible to stop. > It is actually quite convenient to also ensure that you can actually > wake up from suspend because that can obviously go wrong. I gather then that the suspend implementation is such that touching the watchdog periodically while suspended is not a problem. Again, can you please tell me how suspend is implemented on at91? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.