linux-kernel - Re: [PATCH v2 1/1] watchdog: mtk_wdt: Remove mtk_wdt_stop() in probe() to prevent the system freeze and it doesn't reboot by watchdog problem

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Date:   Wed, 30 Dec 2020 08:50:42 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Freddy Hsin <freddy.hsin@...iatek.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     wsd_upstream@...iatek.com, chang-an.chen@...iatek.com,
        kuohong.wang@...iatek.com
Subject: Re: [PATCH v2 1/1] watchdog: mtk_wdt: Remove mtk_wdt_stop() in
 probe() to prevent the system freeze and it doesn't reboot by watchdog
 problem

On 12/30/20 12:15 AM, Freddy Hsin wrote:
> From: "freddy.hsin" <freddy.hsin@...iatek.com>
> 
> Before user space daemon start to access the watchdog device,
> there is a time interval that watchdog is disabled in the
> original flow. If the system freezing at this interval, it
> cannot be rebooted by watchdog hardware automatically.
> 
> In order to solve this problem, the watchdog hardware should be
> kept working, and start hrtimer in framework to ping it by
> setting max_hw_heartbeat_ms and HW_RUNNING used in
> watchdog_need_worker to determine whether the worker should be
> started or not. Besides the redundant setting of max_timeout is
> also removed.
> 
> Signed-off-by: freddy.hsin <freddy.hsin@...iatek.com>
> ---

Change log goes here.

Looks good though.

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

>  drivers/watchdog/mtk_wdt.c |   17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
> index d6a6393..0c869b7 100644
> --- a/drivers/watchdog/mtk_wdt.c
> +++ b/drivers/watchdog/mtk_wdt.c
> @@ -195,6 +195,19 @@ static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
>  	return 0;
>  }
>  
> +static void mtk_wdt_init(struct watchdog_device *wdt_dev)
> +{
> +	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
> +	void __iomem *wdt_base;
> +
> +	wdt_base = mtk_wdt->wdt_base;
> +
> +	if (readl(wdt_base + WDT_MODE) & WDT_MODE_EN) {
> +		set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
> +		mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
> +	}
> +}
> +
>  static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
>  {
>  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
> @@ -264,7 +277,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>  	mtk_wdt->wdt_dev.info = &mtk_wdt_info;
>  	mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
>  	mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
> -	mtk_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
> +	mtk_wdt->wdt_dev.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT * 1000;
>  	mtk_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;
>  	mtk_wdt->wdt_dev.parent = dev;
>  
> @@ -274,7 +287,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>  
>  	watchdog_set_drvdata(&mtk_wdt->wdt_dev, mtk_wdt);
>  
> -	mtk_wdt_stop(&mtk_wdt->wdt_dev);
> +	mtk_wdt_init(&mtk_wdt->wdt_dev);
>  
>  	watchdog_stop_on_reboot(&mtk_wdt->wdt_dev);
>  	err = devm_watchdog_register_device(dev, &mtk_wdt->wdt_dev);
>