linux-kernel - Re: [PATCH] watchdog: imx_sc_wdt: Don't disable WDT in suspend

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Message-ID: <2936c3cc-acdc-4bbd-9dd8-871d5f04b841@roeck-us.net>
Date: Thu, 1 Aug 2024 07:16:38 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Jonas Blixt <jonas.blixt@...ia.se>, wim@...ux-watchdog.org,
 shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
 festevam@...il.com, linux-watchdog@...r.kernel.org, imx@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: john.ernberg@...ia.se, Anson Huang <anson.huang@....com>
Subject: Re: [PATCH] watchdog: imx_sc_wdt: Don't disable WDT in suspend

On 8/1/24 05:18, Jonas Blixt wrote:
> Parts of the suspend and resume chain is left unprotected if we disable
> the WDT here.
> 
>>>From experiments we can see that the SCU disables and re-enables the WDT
> when we enter and leave suspend to ram. By not touching the WDT here we
> are protected by the WDT all the way to the SCU.
> 
> CC: Anson Huang <anson.huang@....com>
> Fixes: 986857acbc9a ("watchdog: imx_sc: Add i.MX system controller watchdog support")
> Signed-off-by: Jonas Blixt <jonas.blixt@...ia.se>

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

> ---
>   drivers/watchdog/imx_sc_wdt.c | 24 ------------------------
>   1 file changed, 24 deletions(-)
> 
> diff --git a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c
> index e51fe1b78518..d73076b686d8 100644
> --- a/drivers/watchdog/imx_sc_wdt.c
> +++ b/drivers/watchdog/imx_sc_wdt.c
> @@ -216,29 +216,6 @@ static int imx_sc_wdt_probe(struct platform_device *pdev)
>   	return devm_watchdog_register_device(dev, wdog);
>   }
>   
> -static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
> -{
> -	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
> -
> -	if (watchdog_active(&imx_sc_wdd->wdd))
> -		imx_sc_wdt_stop(&imx_sc_wdd->wdd);
> -
> -	return 0;
> -}
> -
> -static int __maybe_unused imx_sc_wdt_resume(struct device *dev)
> -{
> -	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
> -
> -	if (watchdog_active(&imx_sc_wdd->wdd))
> -		imx_sc_wdt_start(&imx_sc_wdd->wdd);
> -
> -	return 0;
> -}
> -
> -static SIMPLE_DEV_PM_OPS(imx_sc_wdt_pm_ops,
> -			 imx_sc_wdt_suspend, imx_sc_wdt_resume);
> -
>   static const struct of_device_id imx_sc_wdt_dt_ids[] = {
>   	{ .compatible = "fsl,imx-sc-wdt", },
>   	{ /* sentinel */ }
> @@ -250,7 +227,6 @@ static struct platform_driver imx_sc_wdt_driver = {
>   	.driver		= {
>   		.name	= "imx-sc-wdt",
>   		.of_match_table = imx_sc_wdt_dt_ids,
> -		.pm	= &imx_sc_wdt_pm_ops,
>   	},
>   };
>   module_platform_driver(imx_sc_wdt_driver);