From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755383AbaIWKow (ORCPT ); Tue, 23 Sep 2014 06:44:52 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:56406 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755293AbaIWKou (ORCPT ); Tue, 23 Sep 2014 06:44:50 -0400 Message-ID: <1411469087.32524.6.camel@lp-lvrv.comap.cz> Subject: Re: [PATCH v2] watchdog: omap_wdt: Add 'early_disable' module parameter From: Rostislav Lisovy To: Guenter Roeck Cc: Wim Van Sebroeck , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, sojkam1@fel.cvut.cz, michal.vokac@comap.cz, Rostislav Lisovy Date: Tue, 23 Sep 2014 12:44:47 +0200 In-Reply-To: <541BAD2C.8080902@roeck-us.net> References: <1410877228-20925-1-git-send-email-lisovy@merica.cz> <20140916154921.GA14725@roeck-us.net> <1410967369.5542.2.camel@lp-lvrv.comap.cz> <541BAD2C.8080902@roeck-us.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Čt, 2014-09-18 at 21:12 -0700, Guenter Roeck wrote: > How about reading the OMAP_WATCHDOG_SPR register ? Unfortunately this would be not only extremely fragile (someone writes correct start sequence followed by some garbage -- WD is running and we are reading garbage) but according to some experiments seems not to work at all (I am reading "0" even for a running WD probably as a result to the pm_runtime_get_sync() call). One of the TI employees on the TI forum confirmed (I know this is not a rock-solid information) that it is not possible to safely determine if the WD is running or not. > Either case, you can not issue a message about the watchdog being > stopped or started if you don't know if it was actually stopped > or started. Also, if you don't really know if the watchdog was > stopped or started, all you can do is to either stop or start it, > without judgment about its previous condition. You are right. I was blinded by our use case where the watchdog is always started by the bootloader. I will wait to see if the WATCHDOG_KEEP_ON will be integrated and then I will add the feature for the omap_wdt. Best regards; Rostislav