Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752195AbbKVOD1 (ORCPT ); Sun, 22 Nov 2015 09:03:27 -0500 Received: from proxima.lp0.eu ([81.2.80.65]:59317 "EHLO proxima.lp0.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751474AbbKVODZ (ORCPT ); Sun, 22 Nov 2015 09:03:25 -0500 Subject: Re: [PATCH 4/10] (Was: [PATCH 4/4]) MIPS: bmips: Convert bcm63xx_wdt to use WATCHDOG_CORE To: Guenter Roeck , "devicetree@vger.kernel.org" , Ralf Baechle , Thomas Gleixner , Jason Cooper , Marc Zyngier , Kevin Cernekee , Florian Fainelli , Wim Van Sebroeck , Miguel Gaio , Maxime Bizon , Linux Kernel Mailing List , linux-mips@linux-mips.org, linux-watchdog@vger.kernel.org References: <5650BFD6.5030700@simon.arlott.org.uk> <5650C08C.6090300@simon.arlott.org.uk> <5650E2FA.6090408@roeck-us.net> <5650E5BB.6020404@simon.arlott.org.uk> <56512937.6030903@roeck-us.net> Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Jonas Gorski From: Simon Arlott Message-ID: <5651CB13.4090704@simon.arlott.org.uk> Date: Sun, 22 Nov 2015 14:02:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <56512937.6030903@roeck-us.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2157 Lines: 52 On 22/11/15 02:32, Guenter Roeck wrote: > On 11/21/2015 01:44 PM, Simon Arlott wrote: >> On 21/11/15 21:32, Guenter Roeck wrote: >>> this is really doing a bit too much in a single patch. >>> Conversion to the watchdog infrastructure should probably be >>> the first step, followed by further optimizations and improvements. >> I've split patch 4 up into 7 patches, which will be patches 4/10..10/10 in this thread. Instead of using bcm63xx_timer_register in #ifdefs, I'll remove most of bcm63xx_timer because it's only used by the watchdog. >>> We have some infrastructure changes in the works which will move >>> the need for soft-timers from individual drivers into the watchdog core. >>> Would this possibly be helpful here ? The timer-driven watchdog ping >>> seems to accomplish pretty much the same. >> >> There is no need for a software timer. This is not a timer-driven >> watchdog ping, there is an unmaskable timer interrupt when the watchdog >> timer has less than 50% remaining. >> > Ok. Maybe I got confused by the interrupt-triggered watchdog ping. > I'll have to look into that much more closely; it is quite unusual > and complex. The explanation is also not easy to understand. > What does "The only way to stop this interrupt" mean ? Repeatedly The interrupt is level triggered at less than 50% of the time remaining. Unless the watchdog is stopped or restarted, the interrupt will not stop occurring. > triggering the interrupt in 1/2, 1/4, 1/8 of the remaining time is > really odd. It's a bit odd but there's no way to ack the interrupt. This seemed like the best approach without adding the complexity of a software timer or trying to mask and unmask the timer interrupt. I don't want to ignore the interrupt entirely because I'd like to know if the watchdog is going to cause a reboot. > On side note, the subject tag should be "watchdog:", not "MIPS:". Fixed. -- Simon Arlott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/