linux-kernel - Re: [PATCH v2 2/3] watchdog: da9063: Make use of pre-configured timeout during probe

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Date:   Sat, 25 Apr 2020 10:50:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Stefan Riedmueller <s.riedmueller@...tec.de>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Support Opensource <support.opensource@...semi.com>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] watchdog: da9063: Make use of pre-configured
 timeout during probe

On Fri, Apr 03, 2020 at 03:07:27PM +0200, Stefan Riedmueller wrote:
> The watchdog might already be running during boot with a timeout set by
> e.g. the bootloader. Make use of this pre-configured timeout instead of
> falling back to the default timeout if no device tree value is given.
> 
> Signed-off-by: Stefan Riedmueller <s.riedmueller@...tec.de>
> Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>

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

> ---
> Changes in v2:
>  - Reworked patch to use the pre-configured timeout onyl as a fallback
>    instead of the default value.
>  - Removed info message.
> ---
>  drivers/watchdog/da9063_wdt.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/watchdog/da9063_wdt.c b/drivers/watchdog/da9063_wdt.c
> index 3d65e92a4e3f..423584252606 100644
> --- a/drivers/watchdog/da9063_wdt.c
> +++ b/drivers/watchdog/da9063_wdt.c
> @@ -46,15 +46,16 @@ static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
>  }
>  
>  /*
> - * Return 0 if watchdog is disabled, else non zero.
> + * Read the currently active timeout.
> + * Zero means the watchdog is disabled.
>   */
> -static unsigned int da9063_wdt_is_running(struct da9063 *da9063)
> +static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
>  {
>  	unsigned int val;
>  
>  	regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
>  
> -	return val & DA9063_TWDSCALE_MASK;
> +	return wdt_timeout[val & DA9063_TWDSCALE_MASK];
>  }
>  
>  static int da9063_wdt_disable_timer(struct da9063 *da9063)
> @@ -191,6 +192,7 @@ static int da9063_wdt_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct da9063 *da9063;
>  	struct watchdog_device *wdd;
> +	unsigned int timeout;
>  
>  	if (!dev->parent)
>  		return -EINVAL;
> @@ -214,13 +216,19 @@ static int da9063_wdt_probe(struct platform_device *pdev)
>  	watchdog_set_restart_priority(wdd, 128);
>  	watchdog_set_drvdata(wdd, da9063);
>  
> -	/* Set default timeout, maybe override it with DT value, scale it */
>  	wdd->timeout = DA9063_WDG_TIMEOUT;
> +
> +	/* Use pre-configured timeout if watchdog is already running. */
> +	timeout = da9063_wdt_read_timeout(da9063);
> +	if (timeout)
> +		wdd->timeout = timeout;
> +
> +	/* Set timeout, maybe override it with DT value, scale it */
>  	watchdog_init_timeout(wdd, 0, dev);
>  	da9063_wdt_set_timeout(wdd, wdd->timeout);
>  
> -	/* Change the timeout to the default value if the watchdog is running */
> -	if (da9063_wdt_is_running(da9063)) {
> +	/* Update timeout if the watchdog is already running. */
> +	if (timeout) {
>  		da9063_wdt_update_timeout(da9063, wdd->timeout);
>  		set_bit(WDOG_HW_RUNNING, &wdd->status);
>  	}