linux-kernel - Re: [PATCH v3 04/12] watchdog: s3c2410: Let kernel kick watchdog

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Message-ID: <20211117133459.GD2435591@roeck-us.net>
Date:   Wed, 17 Nov 2021 05:34:59 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Sam Protsenko <semen.protsenko@...aro.org>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v3 04/12] watchdog: s3c2410: Let kernel kick watchdog

On Sun, Nov 07, 2021 at 10:29:35PM +0200, Sam Protsenko wrote:
> When "tmr_atboot" module param is set, the watchdog is started in
> driver's probe. In that case, also set WDOG_HW_RUNNING bit to let
> watchdog core driver know it's running. This way watchdog core can kick
> the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is
> enabled), until user space takes control.
> 
> WDOG_HW_RUNNING bit must be set before registering the watchdog. So the
> "tmr_atboot" handling code is moved before watchdog registration, to
> avoid performing the same check twice. This is also logical because
> WDOG_HW_RUNNING bit makes WDT core expect actually running watchdog.
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>

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

> ---
> Changes in v3:
>   - Added R-b tag by Krzysztof Kozlowski
> 
> Changes in v2:
>   - Added explanation on moving the code block to commit message
>   - [PATCH 03/12] handles the case when tmr_atboot is present but valid
>     timeout wasn't found
> 
>  drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 00421cf22556..0845c05034a1 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -604,6 +604,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  	wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt);
>  	wdt->wdt_device.parent = dev;
>  
> +	/*
> +	 * If "tmr_atboot" param is non-zero, start the watchdog right now. Also
> +	 * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog.
> +	 *
> +	 * If we're not enabling the watchdog, then ensure it is disabled if it
> +	 * has been left running from the bootloader or other source.
> +	 */
> +	if (tmr_atboot) {
> +		dev_info(dev, "starting watchdog timer\n");
> +		s3c2410wdt_start(&wdt->wdt_device);
> +		set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status);
> +	} else {
> +		s3c2410wdt_stop(&wdt->wdt_device);
> +	}
> +
>  	ret = watchdog_register_device(&wdt->wdt_device);
>  	if (ret)
>  		goto err_cpufreq;
> @@ -612,17 +627,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_unregister;
>  
> -	if (tmr_atboot) {
> -		dev_info(dev, "starting watchdog timer\n");
> -		s3c2410wdt_start(&wdt->wdt_device);
> -	} else {
> -		/* if we're not enabling the watchdog, then ensure it is
> -		 * disabled if it has been left running from the bootloader
> -		 * or other source */
> -
> -		s3c2410wdt_stop(&wdt->wdt_device);
> -	}
> -
>  	platform_set_drvdata(pdev, wdt);
>  
>  	/* print out a statement of readiness */
> -- 
> 2.30.2
>