From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND Date: Mon, 9 Mar 2015 08:55:46 +0100 Message-ID: <20150309075546.GY3989@piout.net> References: <1425287898-15093-6-git-send-email-boris.brezillon@free-electrons.com> <20150307110645.GW3989@piout.net> <20150307112932.GA1372@amd> <1615214.0rkGfM1gZL@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1615214.0rkGfM1gZL@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org To: "Rafael J. Wysocki" 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 List-Id: linux-serial@vger.kernel.org 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. -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com