linux-kernel - Re: [PATCH] watchdog: sp805: fix restart handler

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Date:   Fri, 27 Mar 2020 13:42:04 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Michael Walle <michael@...le.cc>, linux-kernel@...r.kernel.org,
        linux-watchdog@...r.kernel.org
Cc:     Jongsung Kim <neidhard.kim@....com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Subject: Re: [PATCH] watchdog: sp805: fix restart handler

On 3/27/20 9:24 AM, Michael Walle wrote:
> The restart handler is missing two things, first, the registers
> has to be unlocked and second there is no synchronization for the
> write_relaxed() calls.
> 
> This was tested on a custom board with the NXP LS1028A SoC.
> 
> Fixes: 6c5c0d48b686c ("watchdog: sp805: add restart handler")
> Signed-off-by: Michael Walle <michael@...le.cc>

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

> ---
>  drivers/watchdog/sp805_wdt.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 53e04926a7b2..190d26e2e75f 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -137,10 +137,14 @@ wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
>  {
>  	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>  
> +	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
>  	writel_relaxed(0, wdt->base + WDTCONTROL);
>  	writel_relaxed(0, wdt->base + WDTLOAD);
>  	writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
>  
> +	/* Flush posted writes. */
> +	readl_relaxed(wdt->base + WDTLOCK);
> +
>  	return 0;
>  }
>  
>