linux-kernel - Re: [PATCH 3/7] watchdog: imx7ulp

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Message-ID: <20220822140557.GB4087281@roeck-us.net>
Date:   Mon, 22 Aug 2022 07:05:57 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Alice Guo (OSS)" <alice.guo@....nxp.com>
Cc:     wim@...ux-watchdog.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, festevam@...il.com, kernel@...gutronix.de,
        linux-imx@....com, linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] watchdog: imx7ulp_wdt: Check CMD32EN in wdog init

On Tue, Aug 16, 2022 at 12:36:39PM +0800, Alice Guo (OSS) wrote:
> From: Ye Li <ye.li@....com>
> 
> When bootloader has enabled the CMD32EN bit, switch to use 32bits
> unlock command to unlock the CS register. Using 32bits command will
> help on avoiding 16 bus cycle window violation for two 16 bits
> commands.
> 
> Signed-off-by: Ye Li <ye.li@....com>
> Signed-off-by: Alice Guo <alice.guo@....com>
> Reviewed-by: Jacky Bai <ping.bai@....com>
> Acked-by: Jason Liu <jason.hui.liu@....com>
> ---
>  drivers/watchdog/imx7ulp_wdt.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c
> index b8ac0cb04d2f..a0f6b8cea78f 100644
> --- a/drivers/watchdog/imx7ulp_wdt.c
> +++ b/drivers/watchdog/imx7ulp_wdt.c
> @@ -180,11 +180,16 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout)
>  
>  	local_irq_disable();
>  
> -	mb();
> -	/* unlock the wdog for reconfiguration */
> -	writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
> -	writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
> -	mb();
> +	val = readl(base + WDOG_CS);
> +	if (val & WDOG_CS_CMD32EN) {
> +		writel(UNLOCK, base + WDOG_CNT);
> +	} else {
> +		mb();
> +		/* unlock the wdog for reconfiguration */
> +		writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
> +		writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
> +		mb();

Now this is intermixing writel() with writel_relaxed(), making
the code all but impossible to understand.

Guenter

> +	}
>  
>  	ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK);
>  	if (ret)
> -- 
> 2.17.1
>