From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 3/3] CBUS: Make retu watchdog behave like a standard Linux watchdog Date: Mon, 12 May 2008 18:17:36 -0700 Message-ID: <20080513011736.GH28999@atomide.com> References: <1210638918-26644-1-git-send-email-tony@atomide.com> <1210638918-26644-2-git-send-email-tony@atomide.com> <1210638918-26644-3-git-send-email-tony@atomide.com> <1210638918-26644-4-git-send-email-tony@atomide.com> <1210639609.20589.13.camel@mort> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mho-01-bos.mailhop.org ([63.208.196.178]:56729 "EHLO mho-01-bos.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756369AbYEMBRg (ORCPT ); Mon, 12 May 2008 21:17:36 -0400 Content-Disposition: inline In-Reply-To: <1210639609.20589.13.camel@mort> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Igor Stoppa Cc: linux-omap@vger.kernel.org * Igor Stoppa [080512 17:56]: > Hi Tony, > On Mon, 2008-05-12 at 17:35 -0700, ext Tony Lindgren wrote: > > Make retu watchdog behave like a standard Linux watchdog. > >=20 > > Let the kernel do the kicking until the watchdog device is opened. >=20 > This is not always the desidered behavior: the powerdown wd is used t= o > ensure that the whole sw stack is healty: doing the kicking in > kernelspace for free introduces the case where userspace can get stuc= k > and the device does not powerdown. That's why there's CONFIG_WATCHDOG_NOWAYOUT where the ping timer is not enabled at all, and the watchdog is just set to max until userspace watchdog software kicking starts. > Also the unconditional loading of the maximum value during probe is n= ot > aligned with the original reset logic, which was to have the powerdow= n > wd to allow for 2 boot attempts: >=20 > -cold boot -> load max value in retu wd (63s) > -> load 30s in omap wd > -try to kick both wds Well you can set those values via /dev/watchdog too, right? And then use CONFIG_WATCHDOG_NOWAYOUT. And ff CONFIG_WATCHDOG_NOWAYOUT is not set, the kernel ping timer only happens when /dev/watchdog is not open. > if fail, then omap reboots, but retu keeps counting down >=20 > -warm boot -> let the retu wd untouched=EF=BB=BF > -> load 30s in omap wd=EF=BB=BF > -try to kick both wds >=20 > if fail, retu powers down >=20 > That was the original idea in 770 times and i still like it. >=20 > To conclude, i'd see inkernel kicking more as a debugging feature whi= le > one is hacking at the kernel than a desirable quality of a stable > kernel. Considering that the /dev/watchdog interface is the standard, I see thi= s patch as the only way we can get this code ever merged upstream. And it= 's easy to patch back the non-standard if you want to. Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html