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Date:   Tue, 31 Mar 2020 09:04:26 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Stefan Riedmueller <s.riedmueller@phytec.de>
Cc:     Wim Van Sebroeck <wim@linux-watchdog.org>,
        Support Opensource <support.opensource@diasemi.com>,
        linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] watchdog: da9062: Use pre-configured timeout until
 userspace takes over
Message-ID: <20200331160426.GA41516@roeck-us.net>
References: <20200326150203.371673-1-s.riedmueller@phytec.de>
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On Thu, Mar 26, 2020 at 04:02:01PM +0100, Stefan Riedmueller wrote:
> If the watchdog is already running during probe read back its
> pre-configured timeout (set e.g. by the bootloader) and use it to ping
> the watchdog until userspace takes over. Otherwise the default timeout
> set before might not result in a fast enough ping.
> 
> Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
> ---
>  drivers/watchdog/da9062_wdt.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
> index 0ad15d55071c..6d81b1276b87 100644
> --- a/drivers/watchdog/da9062_wdt.c
> +++ b/drivers/watchdog/da9062_wdt.c
> @@ -35,6 +35,14 @@ struct da9062_watchdog {
>  	bool use_sw_pm;
>  };
>  
> +static unsigned int da9062_wdt_read_timeout(struct da9062_watchdog *wdt)
> +{
> +	int val;
> +
> +	regmap_read(wdt->hw->regmap, DA9062AA_CONTROL_D, &val);
> +	return wdt_timeout[val & DA9062AA_TWDSCALE_MASK];
> +}
> +
>  static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
>  {
>  	unsigned int i;
> @@ -184,6 +192,7 @@ static int da9062_wdt_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	int ret;
> +	int timeout;
>  	struct da9062 *chip;
>  	struct da9062_watchdog *wdt;
>  
> @@ -213,6 +222,13 @@ static int da9062_wdt_probe(struct platform_device *pdev)
>  	watchdog_set_drvdata(&wdt->wdtdev, wdt);
>  	dev_set_drvdata(dev, &wdt->wdtdev);
>  
> +	timeout = da9062_wdt_read_timeout(wdt);
> +	if (timeout > 0) {
> +		wdt->wdtdev.timeout = timeout;
> +		set_bit(WDOG_HW_RUNNING, &wdt->wdtdev.status);
> +		dev_info(wdt->hw->dev, "watchdog is running (%u s)", timeout);
> +	}

Oh, and I agree with the comment made for the da9063 driver: This driver
should really implement watchdog_init_timeout() and set the default timeout
accordingly if specified in dt (or, in other words, follow the da9063
implementation).

Guenter

> +
>  	ret = devm_watchdog_register_device(dev, &wdt->wdtdev);
>  	if (ret < 0)
>  		return ret;