From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA8AEC433E0 for ; Wed, 29 Jul 2020 15:49:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE7AC207E8 for ; Wed, 29 Jul 2020 15:49:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MjzyvjS+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726757AbgG2PtQ (ORCPT ); Wed, 29 Jul 2020 11:49:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726365AbgG2PtP (ORCPT ); Wed, 29 Jul 2020 11:49:15 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4049C061794; Wed, 29 Jul 2020 08:49:15 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id c6so2047320pje.1; Wed, 29 Jul 2020 08:49:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:autocrypt:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=gLnaOO+zAY+8NlU+JjiWFf2IL/CZfK/QEDabV8C9b7o=; b=MjzyvjS+g0iu3rTZhiWOY6vBVfMn1XtoUyGLeHzgyZFkDiwRoY9Ng0+Eo+blFNAEKN XGM1cx1rpxlHAyFxqXUAUFO3nNGCTkJQ8HtfyGVGLO9xoLbLz1en6UuRIVdBOfpi/QrE 23gzZ0xRZAmTcrZy1J+bfVuHEdsMB4Vl5YooHW+LT3fryCFEmqC623EEhd2icvjIq7zB FPTdn1g2gG7comzuk8cxpr3SR+PlrvMKLzZtyCIZq9UONCtlCu1QW2Ijx6kzVSd7oKZw 5rjL7+OVMdINEFtqgqGmLv3ortSaKMcZJlk90tuvRU8L/cHXLzqtzJOh7Eo84av+4gSB ZzfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=gLnaOO+zAY+8NlU+JjiWFf2IL/CZfK/QEDabV8C9b7o=; b=MmAiVkdQTEuQ0B2IEmdFSxX/XT7Gu33uDPifii/lSoPDxN4K8o2si6jvEC3Zjjqd2L 2stYF2eWq5T8sc6uE8xQTaK9htUpcu3QXNyWs3mVRz+euUfUob0pI9iUqMwQKEJ4EXvM xoEMCpaEHW6C0sINZGPg0J3OZNzuQiauQk3EdM3YqMIhNgqxi4HYiV6ebOQdCi7KMNGx rM5zsjjwyCJIUQLiB01qzk5cgJrcYFf9HbY6diwnjK5afcOyiAgKK2V02KYrmYl1tIb1 DZTNRHWYUUPCZLMUBmofy1crpjUrU0vcqB9jFHGsWxFdXtd1OXF2FSd9JfXkIVJV/rkO Jedw== X-Gm-Message-State: AOAM531C+h9U2+7P63/gVBerFFEqHftPH26GKfrz6jQwrIKDX2yleEIg z0Tb8crH7FyGmoSpFlNbjuA= X-Google-Smtp-Source: ABdhPJwj30BNrHgShCDgRrKFE5t6TVJTZEpfs4pUb3XX8t15TXPiVJDN1rSFX9roK0d8MU7OhbYHEg== X-Received: by 2002:a17:90b:18b:: with SMTP id t11mr10478129pjs.105.1596037755366; Wed, 29 Jul 2020 08:49:15 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id g19sm2693002pfb.152.2020.07.29.08.49.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jul 2020 08:49:14 -0700 (PDT) Subject: Re: [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence for wdog operations To: Anson Huang , "wim@linux-watchdog.org" , "shawnguo@kernel.org" , "s.hauer@pengutronix.de" , "kernel@pengutronix.de" , "festevam@gmail.com" , "linux-watchdog@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Cc: dl-linux-imx References: <1595989227-24700-1-git-send-email-Anson.Huang@nxp.com> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= Message-ID: <2e962b44-d1eb-f060-f1d2-a079322d4c22@roeck-us.net> Date: Wed, 29 Jul 2020 08:49:12 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 7/29/20 8:32 AM, Anson Huang wrote: > Hi, Guenter > > >> Subject: Re: [PATCH V2 1/2] watchdog: imx7ulp: Strictly follow the sequence >> for wdog operations >> >> On 7/28/20 7:20 PM, Anson Huang wrote: >>> According to reference manual, the i.MX7ULP WDOG's operations should >>> follow below sequence: >>> >>> 1. disable global interrupts; >>> 2. unlock the wdog and wait unlock bit set; 3. reconfigure the wdog >>> and wait for reconfiguration bit set; 4. enabel global interrupts. >>> >>> Strictly follow the recommended sequence can make it more robust. >>> >>> Signed-off-by: Anson Huang >>> --- >>> Changes since V1: >>> - use readl_poll_timeout_atomic() instead of usleep_ranges() since IRQ is >> disabled. >>> --- >>> drivers/watchdog/imx7ulp_wdt.c | 29 +++++++++++++++++++++++++++++ >>> 1 file changed, 29 insertions(+) >>> >>> diff --git a/drivers/watchdog/imx7ulp_wdt.c >>> b/drivers/watchdog/imx7ulp_wdt.c index 7993c8c..7d2b12e 100644 >>> --- a/drivers/watchdog/imx7ulp_wdt.c >>> +++ b/drivers/watchdog/imx7ulp_wdt.c >>> @@ -5,6 +5,7 @@ >>> >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -36,6 +37,7 @@ >>> #define DEFAULT_TIMEOUT 60 >>> #define MAX_TIMEOUT 128 >>> #define WDOG_CLOCK_RATE 1000 >>> +#define WDOG_WAIT_TIMEOUT 10000 >>> >>> static bool nowayout = WATCHDOG_NOWAYOUT; >> module_param(nowayout, >>> bool, 0000); @@ -48,17 +50,31 @@ struct imx7ulp_wdt_device { >>> struct clk *clk; >>> }; >>> >>> +static inline void imx7ulp_wdt_wait(void __iomem *base, u32 mask) { >>> + u32 val = readl(base + WDOG_CS); >>> + >>> + if (!(val & mask)) >>> + WARN_ON(readl_poll_timeout_atomic(base + WDOG_CS, val, >>> + val & mask, 0, >>> + WDOG_WAIT_TIMEOUT)); >>> +} >>> + >>> static void imx7ulp_wdt_enable(struct watchdog_device *wdog, bool >>> enable) { >>> struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog); >>> >>> u32 val = readl(wdt->base + WDOG_CS); >>> >>> + local_irq_disable(); >>> writel(UNLOCK, wdt->base + WDOG_CNT); >>> + imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK); >>> if (enable) >>> writel(val | WDOG_CS_EN, wdt->base + WDOG_CS); >>> else >>> writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS); >>> + imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS); >>> + local_irq_enable(); >>> } >>> >>> static bool imx7ulp_wdt_is_enabled(void __iomem *base) @@ -72,7 >>> +88,12 @@ static int imx7ulp_wdt_ping(struct watchdog_device *wdog) { >>> struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog); >>> >>> + local_irq_disable(); >>> + writel(UNLOCK, wdt->base + WDOG_CNT); >>> + imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK); >>> writel(REFRESH, wdt->base + WDOG_CNT); >>> + imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS); >> >> Per reference manual (section 59.5.4), the waits are not required here, and >> neither is the unlock. For practical purposes, disabling interrupts is useless as >> well since the refresh write operation is just a single register write. > > Correct, the example in reference manual does NOT have this flow for refresh, but > I checked with our design team yestoday, their validation code indeed has this flow, > that is why I added it for refresh operation as well. If it is needed, they'll need to update the manual. Urgently. Really, missing the information that the watchdog must be unlocked in order to refresh the timer would not just be be a minor flaw in the manual. Either it is needed and must be mentioned (because the watchdog would otherwise simply not work), or it isn't needed and should not be done. Thanks, Guenter > I will do a test on our EVK board, and if it works without this flow, I will remove them > In V3. > > Thanks, > Anson > > > >