On 21/04/21 18:42, Guenter Roeck wrote:
> On Wed, Apr 21, 2021 at 06:26:21PM +0200, Francesco Zanella wrote:
>> If "start-at-boot" property is present in the device tree, start pinging
>> hw watchdog at probe, in order to take advantage of kernel configs:
>> - WATCHDOG_HANDLE_BOOT_ENABLED: Avoid possible reboot if hw watchdog was
>> been enabled before the kernel (by uboot for example) and userspace
>> doesn't take control of /dev/watchdog in time;
>> - WATCHDOG_OPEN_TIMEOUT: Reboot if userspace doesn't take control of
>> /dev/watchdog within the timeout.
>>
>> Signed-off-by: Francesco Zanella <francesco.zanella@xxxxxxxxx>
>> ---
>> drivers/watchdog/gpio_wdt.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
>> index 0923201ce874..1e6f0322ab7a 100644
>> --- a/drivers/watchdog/gpio_wdt.c
>> +++ b/drivers/watchdog/gpio_wdt.c
>> @@ -31,6 +31,7 @@ struct gpio_wdt_priv {
>> struct gpio_desc *gpiod;
>> bool state;
>> bool always_running;
>> + bool start_at_boot;
>> unsigned int hw_algo;
>> struct watchdog_device wdd;
>> };
>> @@ -147,6 +148,9 @@ static int gpio_wdt_probe(struct platform_device *pdev)
>> priv->always_running = of_property_read_bool(np,
>> "always-running");
>>
>> + priv->start_at_boot = of_property_read_bool(np,
>> + "start-at-boot");
>> +
>> watchdog_set_drvdata(&priv->wdd, priv);
>>
>> priv->wdd.info = &gpio_wdt_ident;
>> @@ -161,7 +165,7 @@ static int gpio_wdt_probe(struct platform_device *pdev)
>>
>> watchdog_stop_on_reboot(&priv->wdd);
>>
>> - if (priv->always_running)
>> + if (priv->always_running || priv->start_at_boot)
>> gpio_wdt_start(&priv->wdd);
>
> So the only real difference to always_running is that always_running
> doesn't stop the watchdog on close but keeps it running.
>
> Does that really warrant another property ? Why not just use
> always-running ?
>
> The special use case of being able to stop the watchdog doesn't seem
> to be worth the trouble. Please explain your use case.
>
> Guenter
>
You got the point.
I would like to be able to stop the watchdog when I want.
>From my point of view always_running is used in the very special
case when the wdt chip can't be stopped.
I want a normal wdt that can be stopped (for example during a system
update), but I want it to start at boot for the 2 reasons that I
explained before:
- I need continuity in hw wdt pinging because I start in uboot,
so I take advantage of WATCHDOG_HANDLE_BOOT_ENABLED that makes
the kernel to do that job; but it is triggered only if it is
started at probe, if I'm not wrong.
- I would like to monitor with the wdt also the kernel at boot,
and more importantly handle the case when the userspace app
doesn't take control of /dev/watchdog for whatever reason
within the timeout set with WATCHDOG_OPEN_TIMEOUT.
Hope that this explain my target.
Thanks for your attention,
Francesco
