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

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Date:   Sat, 2 Oct 2021 15:43:08 +0200
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Mark Pearson <markpearson@...ovo.com>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: iTCO_wdt: Full reinitialize on resume

On 2021-10-02T06:23-0700, Guenter Roeck wrote:
> 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.

Thanks, I'll change that for v2.

> > 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

Is the current way with the dmi table the correct way to do it?

I'm also CC-ing Mark Person from Lenovo who may be able to take a look and
ask their firmware team to maybe fix this on their side.

Thomas