Re: [PATCH] watchdog: renesas_wdt: add grace period before rebooting

From: Guenter Roeck <linux@roeck-us.net>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	linux-watchdog@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH] watchdog: renesas_wdt: add grace period before rebooting
Date: Mon, 18 Jan 2021 08:03:37 -0800	[thread overview]
Message-ID: <3557f4a2-b401-c622-2dc4-282efdebcb11@roeck-us.net> (raw)
In-Reply-To: <20210118094558.36814-1-wsa+renesas@sang-engineering.com>

On 1/18/21 1:45 AM, Wolfram Sang wrote:
> arm64 does not have a grace period after calling reset handlers. It is
> rightfully assumed that watchdog drivers should wait because they know
> the time needed. Implement this for the Renesas watchdog driver.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

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

> ---
>  drivers/watchdog/renesas_wdt.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index d2b5074bca65..5791198960e6 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -151,6 +151,9 @@ static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
>  
>  	rwdt_write(priv, RWTCSRA_TME, RWTCSRA);
>  
> +	/* wait 2 cycles, so watchdog will trigger */
> +	udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate));
> +
>  	return 0;
>  }
>  
>