From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752449AbcDUIrN (ORCPT ); Thu, 21 Apr 2016 04:47:13 -0400 Received: from www.linutronix.de ([62.245.132.108]:48006 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751240AbcDUIrK (ORCPT ); Thu, 21 Apr 2016 04:47:10 -0400 Date: Thu, 21 Apr 2016 10:45:38 +0200 (CEST) From: Thomas Gleixner To: "fixed-term.Oleksij.Rempel" cc: Daniel Lezcano , linux-kernel@vger.kernel.org, "Dirk.Behme" Subject: Re: clockevent driver as source for pretimout watchdog interrupt In-Reply-To: <57186D9B.6000006@de.bosch.com> Message-ID: References: <57186D9B.6000006@de.bosch.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 21 Apr 2016, fixed-term.Oleksij.Rempel wrote: > i'm doing research on proper implementation for watchdog pretimout > interrupt for devices which do not provide this functionality. > > Some watchdog controllers like Freescale iMX6 can generate an interrupt > for some configured time before watchdog will reset the system. > Suddenly most watchdog controllers don't have this functionality. > > My idea is to reuse some count down (one shot?) timer: > - configure it to generate an interrupt for a time less then watchdog > deadline. > - reset it each time we get a ping, before an interrupt is generated. > - interrupt should executed one of governors from pretimout patchset, > see the link: > https://www.mail-archive.com/linux-watchdog@vger.kernel.org/msg02394.html > > I assume clocksource framework is kind of suitable for this purpose? Is > it correct assumption? > Any other ideas? Suggestions? What's wrong with simply using a hrtimer for this? The extra clockevent is not buying you anything AFAICT. Thanks, tglx