On Mon, Sep 21, 2020 at 11:01:37AM +0200, Stefan Roese wrote: > Hi Michael, > Hi Chris, > > On 15.09.20 12:44, Chris Packham wrote: > > > > > > On Tue, 15 Sep 2020, 7:54 PM Michael Walle, <mich...@walle.cc> wrote: > > > > Am 2020-09-15 09:44, schrieb Rayagonda Kokatanur: > > > On Tue, Sep 15, 2020 at 12:56 PM Michael Walle <mich...@walle.cc> > > > wrote: > > >> > > >> Hi Stefan, > > >> > > >> it appears that since commit 06985289d45 ("watchdog: Implement > > generic > > >> watchdog_reset() version") - by default - the first watchdog is > > >> started > > >> unconditionally if CONFIG_WDT is set but never stopped before > > booting > > >> the operating system. > > >> > > >> Shouldn't it also be stopped uncondionally? What's worse is that on > > >> one > > >> board/arch the watchdog is stopped in arch_preboot_os() which is > > never > > >> called in the bootefi case. So even if I'd do a workaround and > > stop it > > >> manually in my board code, I couldn't do that consistently for > > >> bootm/bootefi. > > >> > > >> Or am I missing something here? > > > > > > Define CONFIG_WATCHDOG. > > > This takes care of resetting wdt. > > > > Yes as along as you're inside the bootloader, but when u-boot hands > > control over the OS the watchdog is not serviced anymore; which wouldn't > > be a problem per se, but it is enabled unconditionally by u-boot. > > > > > > Just to add some data. At $dayjob we use this behaviour as a failsafe to > > make sure our userspace gets to a point where it is servicing the > > watchdog. > > Yes, this is exactly how this is supposed to work AFAIK. > > Michael, are you sure that the watchdog was disabled in U-Boot when > booting into the OS before this patch? > > > That said having a leave-wdt-running environment variable would work for > > our use case. > > I would rather use it the other way around. Something like "wdt-stop- > pre-os" to optionally stop the WDT before booting into the OS. > > Remark: > IMHO, if you don't use the WDT in the OS, it does not make much sense > to enable the WDT in U-Boot.
Yes, we need to be very careful about making it so that a watchdog is disabled and not re-enabled before moving on for a whole bunch of reasons. And the best option would be to just disable the watchdog if it won't be used while the device is running the OS. -- Tom
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