Hi Guenter, On Thu, 2016-12-15 at 12:46 -0500, Sylvain Lemieux wrote: > 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). > [...] > I took the "watchdog: gpio: keepalives" patch and rebase this patch on top of it. We have a scenario that will open and close the GPIO watchdog device a few times during the user-space initialization. This scenario is working properly with this patch on top of v4.9. With the "watchdog: gpio: keepalives", I am getting an error when the GPIO watchdog driver is open for the 3rd time during this initialization process. This is a short summary of stack trace: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 808 at lib/kobject.c:597 kobject_get+0x6c/0xac kobject: '(null)' (c397f304): is not initialized, yet kobject_get() is being called. ... [<c01a97f8>] (kobject_get) from [<c00c1278>] (chrdev_open+0x54/0x21c) [<c00c1224>] (chrdev_open) from [<c00b9df0>] (do_dentry_open +0x188/0x2d8) ... [<c00cabcc>] (do_filp_open) from [<c00bb668>] (do_sys_open+0x114/0x1cc) [<c00bb554>] (do_sys_open) from [<c00bb74c>] (SyS_open+0x2c/0x30) [<c00bb720>] (SyS_open) from [<c000f840>] (ret_fast_syscall+0x0/0x38) [ 16.807133] ---[ end trace 7d55a0fe58991d4c ]--- [ 16.807143] ------------[ cut here ]------------ Regards, Sylvain > > > 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
