linux-kernel - Re: [PATCH 4/7] watchdog: imx7ulp

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Message-ID: <20220822140946.GC4087281@roeck-us.net>
Date:   Mon, 22 Aug 2022 07:09:46 -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 4/7] watchdog: imx7ulp_wdt: Fix RCS timeout issue

On Tue, Aug 16, 2022 at 12:36:40PM +0800, Alice Guo (OSS) wrote:
> From: Ye Li <ye.li@....com>
> 
> According to measure on i.MX7ULP and i.MX8ULP, the RCS done needs
> about 3400us and 6700us respectively. So current 20us timeout is
> not enough. When reconfiguring is on-going, unlock and configure CS
> will lead to unknown result.
> 
> Increase the wait timeout value to 10ms and check the return value
> of RCS wait to fix the issue
> 

You'll have to find a better solution. An active (non-sleep) wait of
10 ms is unacceptable.

Guenter

> 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 | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c
> index a0f6b8cea78f..12715c248688 100644
> --- a/drivers/watchdog/imx7ulp_wdt.c
> +++ b/drivers/watchdog/imx7ulp_wdt.c
> @@ -39,7 +39,7 @@
>  #define DEFAULT_TIMEOUT	60
>  #define MAX_TIMEOUT	128
>  #define WDOG_CLOCK_RATE	1000
> -#define WDOG_WAIT_TIMEOUT	20
> +#define WDOG_WAIT_TIMEOUT	10000
>  
>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  module_param(nowayout, bool, 0000);
> @@ -80,7 +80,7 @@ static int imx7ulp_wdt_enable(struct watchdog_device *wdog, bool enable)
>  		writel(val | WDOG_CS_EN, wdt->base + WDOG_CS);
>  	else
>  		writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS);
> -	imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> +	ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
>  
>  enable_out:
>  	local_irq_enable();
> @@ -127,7 +127,9 @@ static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
>  	if (ret)
>  		goto timeout_out;
>  	writel(val, wdt->base + WDOG_TOVAL);
> -	imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> +	ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> +	if (ret)
> +		goto timeout_out;
>  
>  	wdog->timeout = timeout;
>  
> -- 
> 2.17.1
>