Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754063AbbKEFNw (ORCPT ); Thu, 5 Nov 2015 00:13:52 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:43852 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbbKEFNt (ORCPT ); Thu, 5 Nov 2015 00:13:49 -0500 Subject: Re: [Linaro-acpi] [PATCH v8 5/5] Watchdog: introduce ARM SBSA watchdog driver To: Timur Tabi , Fu Wei References: <1445961999-9506-1-git-send-email-fu.wei@linaro.org> <1445961999-9506-6-git-send-email-fu.wei@linaro.org> Cc: Linaro ACPI Mailman List , linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, lkml , linux-doc@vger.kernel.org, "Rafael J. Wysocki" , Arnd Bergmann , Jonathan Corbet , Jon Masters , Pratyush Anand , Will Deacon , Wim Van Sebroeck , Catalin Marinas , Wei Fu , Rob Herring , Vipul Gandhi , Dave Young From: Guenter Roeck Message-ID: <563AE588.1080009@roeck-us.net> Date: Wed, 4 Nov 2015 21:13:44 -0800 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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1545 Lines: 36 On 11/04/2015 05:59 PM, Timur Tabi wrote: > On Tue, Oct 27, 2015 at 11:06 AM, wrote: >> +static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id) >> +{ >> + struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id; >> + struct watchdog_device *wdd = &gwdt->wdd; >> + >> + /* We don't use pretimeout, trigger WS1 now */ >> + if (!wdd->pretimeout) >> + sbsa_gwdt_set_wcv(wdd, 0); > > So I'm still concerned about the fact this driver depends on an > interrupt handler in order to properly program the hardware. Unlike > some other devices, the SBSA watchdog does not need assistance to > reset on a timeout -- it is a "fire and forget" device. What happens > if there is a hard lockup, and interrupts no longer work? > > Keep in mind that 99% of watchdog daemons will not enable the > pre-timeout feature because it's new. > Same here, really. I would feel much more comfortable if the driver would just use the standard watchdog timeout and live with (worst case) 20 seconds timeout for now. This limitation will be gone once the infrastructure is in place to handle such short timeouts in the watchdog core. Until then, I would argue that the system designers asked for it if they really select the highest possible clock rate. Guenter -- 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/