On Thu, Dec 17, 2020 at 10:51:08AM -0600, Rob Herring wrote: > On Fri, Dec 11, 2020 at 5:10 PM Rasmus Villemoes > <rasmus.villemoes@xxxxxxxxx> wrote: > > > > On 11/12/2020 23.30, Rob Herring wrote: > > > On Fri, Dec 11, 2020 at 3:56 PM Rasmus Villemoes > > > <rasmus.villemoes@xxxxxxxxx> wrote: > > >> > > >> Some RTCs, e.g. the pcf2127, can be used as a hardware watchdog. But > > >> if the reset pin is not actually wired up, the driver exposes a > > >> watchdog device that doesn't actually work. > > >> > > >> Provide a standard binding that can be used to indicate that a given > > >> RTC can perform a reset of the machine, similar to wakeup-source. > > > > > > Why not use the watchdog 'timeout-sec' property? > > > > Wouldn't that be overloading that property? AFAIU, that is used to ask > > the kernel to program an initial timeout value into the watchdog device. > > But what if one doesn't want to start the watchdog device at kernel > > boot, but just indicate that the RTC has that capability? > > Yeah, I guess you're right. I agree, too. The initial suggestion looks fine. > > It's quite possible that if it can act as a watchdog device (and > > has-watchdog was also suggested), one would also want timeout-sec and > > other watchdog bindings to apply. But that can be added later, by those > > who actually want that. > > > > For now, I'd really like to get my board booting again (or rather, not > > get reset by the real watchdog just because the pcf2127 driver now > > exposes something as /dev/wathdog0, pushing the real one to > > /dev/wathcdog1 which doesn't get pinged from userspace). > > I'm wondering how you solve which wdog to ping when there are multiple > without relying on numbering. I guess 'reset-source' will solve that > even if that's not your current fix. So I guess I'm fine with this. I guess you'd need some udev magic that ensures that the right watchdog always gets the same number. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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