Re: [PATCH v2 1/1] watchdog: atmel: atmel-sama5d4-wdt: Disable watchdog on system suspend

Alexandre Belloni
2019-06-20T08:33:18Z

On 14/06/2019 12:53:22+0000, Ken Sloat wrote:
> From: Ken Sloat <ksloat@aampglobal.com>
>
> Currently, the atmel-sama5d4-wdt continues to run after system suspend.
> Unless the system resumes within the watchdog timeout period so the
> userspace can kick it, the system will be reset. This change disables
> the watchdog on suspend if it is active and re-enables on resume. These
> actions occur during the late and early phases of suspend and resume
> respectively to minimize chances where a lock could occur while the
> watchdog is disabled.
>
> Signed-off-by: Ken Sloat <ksloat@aampglobal.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
> Changes in v2:
> -Consolidate resume and resume early statements.
>
> drivers/watchdog/sama5d4_wdt.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index 111695223aae..0d123f8cbcc6 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -280,7 +280,17 @@ static const struct of_device_id sama5d4_wdt_of_match[] = {
> MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
>
> #ifdef CONFIG_PM_SLEEP
> -static int sama5d4_wdt_resume(struct device *dev)
> +static int sama5d4_wdt_suspend_late(struct device *dev)
> +{
> + struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&wdt->wdd))
> + sama5d4_wdt_stop(&wdt->wdd);
> +
> + return 0;
> +}
> +
> +static int sama5d4_wdt_resume_early(struct device *dev)
> {
> struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
>
> @@ -291,12 +301,17 @@ static int sama5d4_wdt_resume(struct device *dev)
> */
> sama5d4_wdt_init(wdt);
>
> + if (watchdog_active(&wdt->wdd))
> + sama5d4_wdt_start(&wdt->wdd);
> +
> return 0;
> }
> #endif
>
> -static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
> - sama5d4_wdt_resume);
> +static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
> + SET_LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
> + sama5d4_wdt_resume_early)
> +};
>
> static struct platform_driver sama5d4_wdt_driver = {
> .probe = sama5d4_wdt_probe,
> --
> 2.17.1
>

--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering