Re: [PATCH 3/5] watchdog: gpio: Support watchdogs with a minimum heartbeat interval

[Guenter Roeck <linux@roeck-us.net>]

On 10/16/26 15:16, Florian Fainelli wrote:
> Read the optional hw-min-interval-ms property into min_hw_heartbeat_ms so
> the watchdog core defers keepalives that would toggle the GPIO too soon.
> Reject zero intervals and intervals at or above the hardware margin.
> Devices without the property retain their existing behavior.
> 
> Remove the arbitrary 65535 ms upper bound on hw_margin_ms as well. There
> is no register width to constrain this software interval, and the MTX-1
> watchdog needs a larger margin with a 1600 ms minimum ping interval.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

For my reference:

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

> ---
>   drivers/watchdog/gpio_wdt.c | 14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
> index ff323d6e692e..a431c77fa179 100644
> --- a/drivers/watchdog/gpio_wdt.c
> +++ b/drivers/watchdog/gpio_wdt.c
> @@ -138,10 +138,20 @@ static int gpio_wdt_probe(struct platform_device *pdev)
>   	ret = device_property_read_u32(dev, "hw_margin_ms", &hw_margin);
>   	if (ret)
>   		return ret;
> -	/* Disallow values lower than 2 and higher than 65535 ms */
> -	if (hw_margin < 2 || hw_margin > 65535)
> +	/* The core feeds the watchdog at half the hardware margin. */
> +	if (hw_margin < 2)
>   		return -EINVAL;
>   
> +	if (device_property_present(dev, "hw-min-interval-ms")) {
> +		ret = device_property_read_u32(dev, "hw-min-interval-ms",
> +					      &priv->wdd.min_hw_heartbeat_ms);
> +		if (ret)
> +			return ret;
> +		if (!priv->wdd.min_hw_heartbeat_ms ||
> +		    priv->wdd.min_hw_heartbeat_ms >= hw_margin)
> +			return -EINVAL;
> +	}
> +
>   	priv->always_running = device_property_read_bool(dev, "always-running");
>   
>   	watchdog_set_drvdata(&priv->wdd, priv);