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=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 7E321C433E0 for ; Sun, 27 Dec 2020 14:12:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D6712250F for ; Sun, 27 Dec 2020 14:12:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726148AbgL0OL5 (ORCPT ); Sun, 27 Dec 2020 09:11:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726178AbgL0OL5 (ORCPT ); Sun, 27 Dec 2020 09:11:57 -0500 Received: from mail-ed1-x52f.google.com (mail-ed1-x52f.google.com [IPv6:2a00:1450:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3773C061795 for ; Sun, 27 Dec 2020 06:11:16 -0800 (PST) Received: by mail-ed1-x52f.google.com with SMTP id g24so7571545edw.9 for ; Sun, 27 Dec 2020 06:11:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ragnatech-se.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=d8buC2n2HJrCX+cz+sXulp+feTndNkLGIjAwCJwK8WQ=; b=cdplkTMbZAS1RVhpArrpmAyxEIETsEqOQbY0f3NG5qgMqHRn9OS79mYQ8MP+YpaSEm 0AO76J6FRvEzZYk9mOkd3LCmwpDgKilZnz7gMHFf6970afhCXgrfj/4XXqLkvoSAulVd 2qXC2tLAiPszwM1HJ527jbxJiwrb99vVaTSt00ELeOuRvu2z0XNm8tWiyS6GIFjskPAw cQsuPr11qxRMRswHjr9D9VeqrmtXGG4tFXvZM5QI87YDC9txiOn3Ov4/lD5qF0tupV3R 5KyTESf0FhsmLJ3yZSNABgBIXSU2qS0ZsCZA0rKFMJA5pPIwi2K5tRIcsUr9Cr8LOevK fCnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=d8buC2n2HJrCX+cz+sXulp+feTndNkLGIjAwCJwK8WQ=; b=lGodY5iPlhRpZX7RpgUtADaBqXv6nwmgaKHhw0xgTTNQNcAE6KEA2zxoBmBCinsXuh tBYrPb+toG5ZI9Exv6VxPpW2YddimKKp1m/Y1u+t59cuaNgKqM2QWdcP4bUR3kiJNOSk oBRdLLEm4UM9XeW5ApnS+y25vA8lGQ5XDU9yQBh6vL2ODH4poTCJe7j5rr24rP9GRZyI B3GU44AS0mb4VWgZyu7+vqVyEMTVFSJ/BJnp3o0/ktC/ujIMcJu/OmHf+NaukWl3IvUv z1svSrbYZqeagpw8v9PBVwRuZg1/7eugUHc/TxCvs1dohdqXgD13jVXRaJ2eoortVHoX gVzw== X-Gm-Message-State: AOAM533UdCnjdCPSP9bmam8apOr9mN+Tv0vO9wcc76f0BPVvGg21KyQe EdBa7oxXmUhZshJ25q/f+MoezQ== X-Google-Smtp-Source: ABdhPJzytDj/MfEqPDN7AY8mOtW9I53pUrkji6gbrhs+L3dA4O4e2nqU+40eSwyijGNwkPfQ+NYT7w== X-Received: by 2002:a50:e8c4:: with SMTP id l4mr38424386edn.337.1609078275288; Sun, 27 Dec 2020 06:11:15 -0800 (PST) Received: from localhost ([192.36.80.8]) by smtp.gmail.com with ESMTPSA id s1sm16263485ejx.25.2020.12.27.06.11.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Dec 2020 06:11:14 -0800 (PST) Date: Sun, 27 Dec 2020 15:11:11 +0100 From: Niklas =?iso-8859-1?Q?S=F6derlund?= To: Wolfram Sang Cc: linux-watchdog@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH] watchdog: renesas_wdt: don't sleep in atomic context Message-ID: References: <20201219173415.21848-1-wsa+renesas@sang-engineering.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201219173415.21848-1-wsa+renesas@sang-engineering.com> Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org Hi Wolfram, Thanks for your work. On 2020-12-19 18:34:15 +0100, Wolfram Sang wrote: > In the restart handler, we hit multiple OOPSes. One because of > usleep_range() and one because of RPM. So, instead of re-using > rwdt_start(), we implement an atomic version of it in the restart > handler. As a little bonus, reboot will occur sooner because we can now > use the smallest divider in the custom restart routine. > > Signed-off-by: Wolfram Sang Reviewed-by: Niklas Söderlund > --- > > It is problematic to add a Fixes: tag because we would need three of > them. So, I'd think we add a stable tag and as long as the patch > applies, all is fine. Other opinions? > > drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------ > 1 file changed, 24 insertions(+), 6 deletions(-) > > diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c > index 47fce4de0110..d2b5074bca65 100644 > --- a/drivers/watchdog/renesas_wdt.c > +++ b/drivers/watchdog/renesas_wdt.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -50,6 +51,7 @@ struct rwdt_priv { > struct watchdog_device wdev; > unsigned long clk_rate; > u8 cks; > + struct clk *clk; > }; > > static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) > @@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) > return DIV_BY_CLKS_PER_SEC(priv, 65536 - val); > } > > +/* needs to be atomic - no RPM, no usleep_range, no scheduling! */ > static int rwdt_restart(struct watchdog_device *wdev, unsigned long action, > void *data) > { > struct rwdt_priv *priv = watchdog_get_drvdata(wdev); > + u8 val; > + > + clk_prepare_enable(priv->clk); > + > + /* Stop the timer before we modify any register */ > + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME; > + rwdt_write(priv, val, RWTCSRA); > + /* Delay 2 cycles before setting watchdog counter */ > + udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate)); > > - rwdt_start(wdev); > rwdt_write(priv, 0xffff, RWTCNT); > + /* smallest divider to reboot soon */ > + rwdt_write(priv, 0, RWTCSRA); > + > + readb_poll_timeout_atomic(priv->base + RWTCSRA, val, > + !(val & RWTCSRA_WRFLG), 1, 100); > + > + rwdt_write(priv, RWTCSRA_TME, RWTCSRA); > + > return 0; > } > > @@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > struct rwdt_priv *priv; > - struct clk *clk; > unsigned long clks_per_sec; > int ret, i; > u8 csra; > @@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) > if (IS_ERR(priv->base)) > return PTR_ERR(priv->base); > > - clk = devm_clk_get(dev, NULL); > - if (IS_ERR(clk)) > - return PTR_ERR(clk); > + priv->clk = devm_clk_get(dev, NULL); > + if (IS_ERR(priv->clk)) > + return PTR_ERR(priv->clk); > > pm_runtime_enable(dev); > pm_runtime_get_sync(dev); > - priv->clk_rate = clk_get_rate(clk); > + priv->clk_rate = clk_get_rate(priv->clk); > csra = readb_relaxed(priv->base + RWTCSRA); > priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0; > pm_runtime_put(dev); > -- > 2.29.2 > -- Regards, Niklas Söderlund