Hi Guenter, On Fri, 2016-12-09 at 13:07 -0800, Guenter Roeck wrote: > On Wed, Dec 07, 2016 at 02:46:20PM -0500, Sylvain Lemieux wrote: > > From: Sylvain Lemieux <slemieux@xxxxxxxxxxx> > > > > There is a need to allow a grace period after the watchdog software > > client has closed. It could be used for syncing the filesystem or > > allow graceful termination while still providing a hardware reset > > in case the system has hung. > > > > The "always-running" configuration from device-tree does not provide > > this since it will automatically keep the hardware watchdog alive as > > soon as the software client closes (i.e. keep toggling the GPIO line > > regardless of the state of the soft part of the watchdog). > > > > The "keep-armed-on-close" member in the GPIO watchdog implementation > > indicates if an expired timeout should cause a reset. > > > > This patch add a new "keep-armed-on-close" device-tree configuration > > that will keep the watchdog "armed" until the next timeout period after > > a close. During this period, the hardware watchdog is kept alive. > > > > A software watchdog client that wants to provide a grace period, > > before a hard reset, can set the timeout before properly closing. > > > > Signed-off-by: Sylvain Lemieux <slemieux@xxxxxxxxxxx> > > Rather than changing the current gpio watchdog code, I would prefer to start > with https://lkml.org/lkml/2016/1/26/517, which moves part of its code into > the watchdog core - even more so here since I suspect that the suggested > changes won't work anymore after the above patch is applied. > I agree that we should apply the "keepalive" change for this driver first; ref. https://lkml.org/lkml/2016/2/28/239 (version v8). There is another change that was submitted to the mailing list, yesterday, that is implementing a similar functionality: "watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT" http://www.spinics.net/lists/linux-watchdog/msg10500.html I will try to look at both change, next week, to see if I can get the same functionality, with them, for the gpio watchdog. > Also, isn't this quite identical to nowayout ? > Nowayout block the watchdog driver from being stop. In this case, we want to stop the watchdog (i.e. close) and be able to reopen it within the timeout period. If the driver is not reopen within the timeout period, the board should reset. Regards, Sylvain > Thanks, > Guenter > > > --- > > Documentation/devicetree/bindings/watchdog/gpio-wdt.txt | 3 +++ > > drivers/watchdog/gpio_wdt.c | 6 ++++++ > > 2 files changed, 9 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > > index 83d2814..2669735 100644 > > --- a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > > +++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > > @@ -17,6 +17,9 @@ Optional Properties: > > - always-running: If the watchdog timer cannot be disabled, add this flag to > > have the driver keep toggling the signal without a client. It will only cease > > to toggle the signal when the device is open and the timeout elapsed. > > +- keep-armed-on-close: if the watchdog timer need to keep toggling the signal > > + when close, until the timeout elapsed, add this flag to have the driver > > + keep toggling the signal, until the timeout elapsed. > > - timeout-sec: Contains the watchdog timeout in seconds. > > - start-at-init: Start kicking watchdog as soon as driver is loaded. > > > > diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c > > index ef9ab91..ba9091a 100644 > > --- a/drivers/watchdog/gpio_wdt.c > > +++ b/drivers/watchdog/gpio_wdt.c > > @@ -32,6 +32,7 @@ struct gpio_wdt_priv { > > bool active_low; > > bool state; > > bool always_running; > > + bool keep_armed_on_close; > > bool armed; > > unsigned int hw_algo; > > unsigned int hw_margin; > > @@ -72,6 +73,9 @@ static int gpio_wdt_stop(struct watchdog_device *wdd) > > { > > struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); > > > > + if(priv->keep_armed_on_close) > > + return 0; > > + > > priv->armed = false; > > if (!priv->always_running) { > > mod_timer(&priv->timer, 0); > > @@ -210,6 +214,8 @@ static int gpio_wdt_probe(struct platform_device *pdev) > > > > priv->always_running = of_property_read_bool(pdev->dev.of_node, > > "always-running"); > > + priv->keep_armed_on_close = of_property_read_bool(pdev->dev.of_node, > > + "keep-armed-on-close"); > > > > watchdog_set_drvdata(&priv->wdd, priv); > > > > -- > > 1.8.3.1 > > -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
