Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161651AbbKEOgA (ORCPT ); Thu, 5 Nov 2015 09:36:00 -0500 Received: from mail-ob0-f172.google.com ([209.85.214.172]:33599 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161392AbbKEOf5 (ORCPT ); Thu, 5 Nov 2015 09:35:57 -0500 MIME-Version: 1.0 In-Reply-To: <563B62F7.3050307@codeaurora.org> References: <1445961999-9506-1-git-send-email-fu.wei@linaro.org> <1445961999-9506-6-git-send-email-fu.wei@linaro.org> <563AE588.1080009@roeck-us.net> <563B5DF9.6080102@codeaurora.org> <563B62F7.3050307@codeaurora.org> Date: Thu, 5 Nov 2015 22:35:57 +0800 Message-ID: Subject: Re: [Linaro-acpi] [PATCH v8 5/5] Watchdog: introduce ARM SBSA watchdog driver From: Fu Wei To: Timur Tabi Cc: Guenter Roeck , 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 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2135 Lines: 68 Hi Timur, On 5 November 2015 at 22:08, Timur Tabi wrote: > Fu Wei wrote: >> >> SBSA 2.3 Page 23 : >> Note: the watchdog offset register is 32 bits wide. This gives a >> maximum watch period of around 10s at a system >> counter frequency of 400MHz. If a larger watch period is required then >> the compare value can be programmed >> directly into the compare value register. >> >> 214s means your system counter is approximately at 20MHz which is in >> the range of (10MHz ~ 400MHz) >> >> SBSA 2.3 Page 13 : >> The System Counter (of the Generic Timer) shall run at a minimum >> frequency of 10MHz and maximum of >> 400MHz. > > > Thanks, that explains a lot. > > If we expected customers to have a lower system counter frequency, then we > wouldn't have to worry about the timeouts being too short. It seems to me > that the SBSA spec says that if you want a longer timeout, you have to lower > the frequency. Did you really read the "Note" above???????? OK, let me paste it again and again: SBSA 2.3 Page 23 : If a larger watch period is required then the compare value can be programmed directly into the compare value register. > We shouldn't be complicating the driver because some > customers might not follow the spec. OK it this customer might not follow the spec, that watchdog is not a SBSA watchdog, So please don't use SBSA watchdog driver on that non-SBSA watchdog device, Thanks a lot > > > -- > Sent by an employee of the Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the > Code Aurora Forum, hosted by The Linux Foundation. -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 -- 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/