From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932457AbaIWQOs (ORCPT ); Tue, 23 Sep 2014 12:14:48 -0400 Received: from mail-pd0-f170.google.com ([209.85.192.170]:64236 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756050AbaIWQOq (ORCPT ); Tue, 23 Sep 2014 12:14:46 -0400 Date: Tue, 23 Sep 2014 09:14:40 -0700 From: Guenter Roeck To: Rostislav Lisovy Cc: Wim Van Sebroeck , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, sojkam1@fel.cvut.cz, michal.vokac@comap.cz, Rostislav Lisovy Subject: Re: [PATCH v2] watchdog: omap_wdt: Add 'early_disable' module parameter Message-ID: <20140923161440.GC20591@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> <1411469087.32524.6.camel@lp-lvrv.comap.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1411469087.32524.6.camel@lp-lvrv.comap.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 23, 2014 at 12:44:47PM +0200, Rostislav Lisovy wrote: > 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. > Annoying, but I guess we'll have to live with that. > > > 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. > I would predict that it will be accepted. For my part I am not happy with the name, though, and I'll have to find the time to thoroughly review and, if possible, test it. Guenter From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pd0-f170.google.com ([209.85.192.170]:64236 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756050AbaIWQOq (ORCPT ); Tue, 23 Sep 2014 12:14:46 -0400 Date: Tue, 23 Sep 2014 09:14:40 -0700 From: Guenter Roeck To: Rostislav Lisovy Cc: Wim Van Sebroeck , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, sojkam1@fel.cvut.cz, michal.vokac@comap.cz, Rostislav Lisovy Subject: Re: [PATCH v2] watchdog: omap_wdt: Add 'early_disable' module parameter Message-ID: <20140923161440.GC20591@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> <1411469087.32524.6.camel@lp-lvrv.comap.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1411469087.32524.6.camel@lp-lvrv.comap.cz> Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org Content-Transfer-Encoding: quoted-printable On Tue, Sep 23, 2014 at 12:44:47PM +0200, Rostislav Lisovy wrote: > On =C4=8Ct, 2014-09-18 at 21:12 -0700, Guenter Roeck wrote: > > How about reading the OMAP_WATCHDOG_SPR register ? >=20 > 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 wor= k > at all (I am reading "0" even for a running WD probably as a result to > the pm_runtime_get_sync() call). >=20 > 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. >=20 Annoying, but I guess we'll have to live with that. >=20 > > 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. >=20 > 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. >=20 I would predict that it will be accepted. For my part I am not happy with the name, though, and I'll have to find the time to thoroughly revie= w and, if possible, test it. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html