[PATCH] watchdog/hpwdt: Support Suspend and Resume

[PATCH] watchdog/hpwdt: Support Suspend and Resume

[Jerry Hoemann]

Add call backs to support suspend and resume.

Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
---
 drivers/watchdog/hpwdt.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index 138dc8d8ca3d..6565cfaa8e57 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -378,11 +378,38 @@ static void hpwdt_exit(struct pci_dev *dev)
 	pci_disable_device(dev);
 }
 
+static int hpwdt_suspend(struct device *dev)
+{
+	dev_dbg(dev, "Suspend watchdog\n");
+
+	if (watchdog_active(&hpwdt_dev))
+		hpwdt_stop();
+
+	return 0;
+}
+
+static int hpwdt_resume(struct device *dev)
+{
+	dev_dbg(dev, "Resume watchdog\n");
+
+	if (watchdog_active(&hpwdt_dev))
+		hpwdt_start(&hpwdt_dev);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(hpwdt_pm_ops, hpwdt_suspend, hpwdt_resume);
+
 static struct pci_driver hpwdt_driver = {
 	.name = "hpwdt",
 	.id_table = hpwdt_devices,
 	.probe = hpwdt_init_one,
 	.remove = hpwdt_exit,
+
+	.driver = {
+		.name = "hpwdt",
+		.pm = &hpwdt_pm_ops,
+	}
 };
 
 MODULE_AUTHOR("Tom Mingarelli");
-- 
2.43.0

Re: [PATCH] watchdog/hpwdt: Support Suspend and Resume

[Guenter Roeck]

On Tue, Feb 13, 2024 at 12:02:03AM -0700, Jerry Hoemann wrote:
> Add call backs to support suspend and resume.
> 

That makes me wonder if we should add something like
	watchdog_stop_on_suspend()
to the watchdog core. Almost every watchdog driver supporting
suspend/resume repeats the same sequence (except for the debug
message). That is a separate question, though.

> Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
> ---
>  drivers/watchdog/hpwdt.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
> index 138dc8d8ca3d..6565cfaa8e57 100644
> --- a/drivers/watchdog/hpwdt.c
> +++ b/drivers/watchdog/hpwdt.c
> @@ -378,11 +378,38 @@ static void hpwdt_exit(struct pci_dev *dev)
>  	pci_disable_device(dev);
>  }
>  
> +static int hpwdt_suspend(struct device *dev)
> +{
> +	dev_dbg(dev, "Suspend watchdog\n");
> +

Doesn't the suspend / resume code already display such debug messages ?

> +	if (watchdog_active(&hpwdt_dev))
> +		hpwdt_stop();
> +
> +	return 0;
> +}
> +
> +static int hpwdt_resume(struct device *dev)
> +{
> +	dev_dbg(dev, "Resume watchdog\n");
> +
> +	if (watchdog_active(&hpwdt_dev))
> +		hpwdt_start(&hpwdt_dev);
> +
> +	return 0;
> +}
> +
> +static DEFINE_SIMPLE_DEV_PM_OPS(hpwdt_pm_ops, hpwdt_suspend, hpwdt_resume);

That disables / enables the watchdog as part of regular suspend/resume
handling, meaning any hang during suspend/resume that happens later will
hang the system. Sure you don't want to use SET_LATE_SYSTEM_SLEEP_PM_OPS()
instead ?

Never mind, though. Your call, obviously.

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

Thanks,
Guenter

Re: [PATCH] watchdog/hpwdt: Support Suspend and Resume

[Jerry Hoemann]

On Tue, Feb 13, 2024 at 08:12:57AM -0800, Guenter Roeck wrote:
> On Tue, Feb 13, 2024 at 12:02:03AM -0700, Jerry Hoemann wrote:
> > Add call backs to support suspend and resume.
> > 
> 
> That makes me wonder if we should add something like
> 	watchdog_stop_on_suspend()
> to the watchdog core. Almost every watchdog driver supporting
> suspend/resume repeats the same sequence (except for the debug
> message). That is a separate question, though.

I think that is a good idea.

> 
> > Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
> > ---
> >  drivers/watchdog/hpwdt.c | 27 +++++++++++++++++++++++++++
> >  1 file changed, 27 insertions(+)
> > 
> > diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
> > index 138dc8d8ca3d..6565cfaa8e57 100644
> > --- a/drivers/watchdog/hpwdt.c
> > +++ b/drivers/watchdog/hpwdt.c
> > @@ -378,11 +378,38 @@ static void hpwdt_exit(struct pci_dev *dev)
> >  	pci_disable_device(dev);
> >  }
> >  
> > +static int hpwdt_suspend(struct device *dev)
> > +{
> > +	dev_dbg(dev, "Suspend watchdog\n");
> > +
> 
> Doesn't the suspend / resume code already display such debug messages ?

It displays some.  I mostly was using to make sure that the
callback was being called.  I can drop it.


> 
> > +	if (watchdog_active(&hpwdt_dev))
> > +		hpwdt_stop();
> > +
> > +	return 0;
> > +}
> > +
> > +static int hpwdt_resume(struct device *dev)
> > +{
> > +	dev_dbg(dev, "Resume watchdog\n");
> > +
> > +	if (watchdog_active(&hpwdt_dev))
> > +		hpwdt_start(&hpwdt_dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static DEFINE_SIMPLE_DEV_PM_OPS(hpwdt_pm_ops, hpwdt_suspend, hpwdt_resume);
> 
> That disables / enables the watchdog as part of regular suspend/resume
> handling, meaning any hang during suspend/resume that happens later will
> hang the system. Sure you don't want to use SET_LATE_SYSTEM_SLEEP_PM_OPS()
> instead ?
> 
> Never mind, though. Your call, obviously.

Your suggestion would be an improvement.
Will change in version 2 of patch.


Thanks for the help.


> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> 
> Thanks,
> Guenter

-- 

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Jerry Hoemann                  Software Engineer   Hewlett Packard Enterprise
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