Hi Timo, Sorry for the late reply. On Fri, 21 Nov 2014 14:23:30 +0200 Timo Kokkonen <timo.kokkonen@xxxxxxxxxx> wrote: > By default the driver will start a kernel timer which keeps on kicking > the watchdog HW until user space has opened the watchdog > device. Usually this is desirable as the watchdog HW is running by > default and the user space may not have any watchdog daemon running at > all. > > However, on production systems it may be mandatory that also early > crashes and lockups will lead to a watchdog reset, even if they happen > before the user space has opened the watchdog device. > > To resolve the issue, add a new device tree property > "enable-early-reset" which will prevent the kernel timer from pinging > the watchdog HW on behalf of user space. The default is still to use > kernel timer, but more strict behavior can be enabled via the device > tree property. > > Signed-off-by: Timo Kokkonen <timo.kokkonen@xxxxxxxxxx> > --- > Documentation/devicetree/bindings/watchdog/atmel-wdt.txt | 4 ++++ > drivers/watchdog/at91sam9_wdt.c | 6 +++++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > index f90e294..a0b7b75 100644 > --- a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt > @@ -28,6 +28,10 @@ Optional properties: > entering idle state. > - atmel,dbg-halt : Should be present if you want to stop the watchdog when > entering debug state. > +- enable-early-reset : Should be present if you want to let the > + watchdog timer to expire even before user space has opened the > + device. If not set, a kernel timer will keep on pinging the > + watchdog until it is opened. If you want to make this property generic, maybe you should document it in a generic binding doc (Documentation/devicetree/bindings/watchdog/watchdog.txt ?). Once you're at it, maybe you could document the generic timeout-sec property in this file. Moreover, you might want to parse this property in watchdog_core.c and store the information in the watchdog_device struct. Apart from that, I'm not opposed to the approach, and I'm fine with the current implementation. Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- 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
