linux-kernel - Re: [PATCH 2/7] watchdog: imx7ulp: Add explict memory barrier for unlock sequence

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Date:   Tue, 16 Aug 2022 08:23:30 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     "Alice Guo (OSS)" <alice.guo@....nxp.com>
Cc:     wim@...ux-watchdog.org, linux@...ck-us.net, shawnguo@...nel.org,
        s.hauer@...gutronix.de, festevam@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-imx@....com, kernel@...gutronix.de,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH 2/7] watchdog: imx7ulp: Add explict memory barrier for
 unlock sequence

On 22-08-16, Alice Guo (OSS) wrote:
> From: Jacky Bai <ping.bai@....com>
> 
> Add explict memory barrier for the wdog unlock sequence.

Did you inspected any failures? It's not enough to say what you did, you
need to specify the why as well.

Regards,
  Marco


> 
> Suggested-by: Ye Li <ye.li@....com>
> Signed-off-by: Jacky Bai <ping.bai@....com>
> Signed-off-by: Alice Guo <alice.guo@....com>
> Reviewed-by: Ye Li <ye.li@....com>
> ---
>  drivers/watchdog/imx7ulp_wdt.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c
> index 014f497ea0dc..b8ac0cb04d2f 100644
> --- a/drivers/watchdog/imx7ulp_wdt.c
> +++ b/drivers/watchdog/imx7ulp_wdt.c
> @@ -179,9 +179,13 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout)
>  	int ret;
>  
>  	local_irq_disable();
> +
> +	mb();
>  	/* unlock the wdog for reconfiguration */
>  	writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
>  	writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
> +	mb();
> +
>  	ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK);
>  	if (ret)
>  		goto init_out;
> -- 
> 2.17.1
> 
> 
>