linux-kernel - Re: [PATCH] watchdog: iTCO_wdt: Full reinitialize on resume

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Date:   Sat, 2 Oct 2021 06:23:03 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Thomas Weißschuh <linux@...ssschuh.net>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: iTCO_wdt: Full reinitialize on resume

On Tue, Sep 28, 2021 at 06:53:43PM +0200, Thomas Weißschuh wrote:
> The Thinkpad T460s always needs driver-side suspend-resume handling.
> If the watchdog is not stopped before suspend then the system will hang
> on resume.
> If the interval is not set before starting the watchdog then the machine
> will instantly be reset after resume.
> 
> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=198019

The Fixes: tag references a SHA, not a bugzilla bug.
> 
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
>  drivers/watchdog/iTCO_wdt.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index 643c6c2d0b72..2297a0a1e5fc 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -47,6 +47,7 @@
>  /* Includes */
>  #include <linux/acpi.h>			/* For ACPI support */
>  #include <linux/bits.h>			/* For BIT() */
> +#include <linux/dmi.h>			/* For DMI matching */
>  #include <linux/module.h>		/* For module specific items */
>  #include <linux/moduleparam.h>		/* For new moduleparam's */
>  #include <linux/types.h>		/* For standard types (like size_t) */
> @@ -605,9 +606,20 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>   */
>  
>  #ifdef CONFIG_ACPI
> +static const struct dmi_system_id iTCO_wdt_force_suspend[] = {
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
> +			DMI_MATCH(DMI_PRODUCT_FAMILY, "ThinkPad T460s"),
> +		},
> +	},
> +	{ },
> +};
> +
>  static inline bool need_suspend(void)
>  {
> -	return acpi_target_system_state() == ACPI_STATE_S0;
> +	return acpi_target_system_state() == ACPI_STATE_S0 ||
> +		dmi_check_system(iTCO_wdt_force_suspend);
>  }
>  #else
>  static inline bool need_suspend(void) { return true; }
> @@ -631,8 +643,10 @@ static int iTCO_wdt_resume_noirq(struct device *dev)
>  {
>  	struct iTCO_wdt_private *p = dev_get_drvdata(dev);
>  
> -	if (p->suspended)
> +	if (p->suspended) {
> +		iTCO_wdt_set_timeout(&p->wddev, p->wddev.timeout);
>  		iTCO_wdt_start(&p->wddev);
> +	}
>  
>  	return 0;
>  }
> 
> base-commit: 41e73feb1024929e75eaf2f7cd93f35a3feb331b
> -- 
> 2.33.0
>