Hi Guenter, ... > >>> The new parameter "start_enabled" starts the watchdog at the same time > >>> of the module insertion. > >>> This feature is very useful in embedded systems, to avoid cases where > >>> the system hangs before reaching userspace. > >>> > >>> This function can be also enabled in the kernel config, so can be > >>> used when the watchdog driver is build as built-in. > >>> > >>> This parameter involves the "core" section of the watchdog driver; > >>> in this way it is common for all the watchdog hardware implementations. > >>> > >>> Note: to use only for watchdog drivers which doesn't support this > >>> parameter by itself. > >>> > >>> Signed-off-by: Flavio Suligoi <f.suligoi@xxxxxxx> > >>> --- > >>> Documentation/watchdog/watchdog-parameters.rst | 5 +++++ > >>> drivers/watchdog/Kconfig | 14 ++++++++++++++ > >>> drivers/watchdog/watchdog_core.c | 12 ++++++++++++ > >>> 3 files changed, 31 insertions(+) > >>> > >>> diff --git a/Documentation/watchdog/watchdog-parameters.rst > >> b/Documentation/watchdog/watchdog-parameters.rst > >>> index 223c99361a30..623fd064df91 100644 > >>> --- a/Documentation/watchdog/watchdog-parameters.rst > >>> +++ b/Documentation/watchdog/watchdog-parameters.rst > >>> @@ -21,6 +21,11 @@ watchdog core: > >>> timeout. Setting this to a non-zero value can be useful to ensure that > >>> either userspace comes up properly, or the board gets reset and allows > >>> fallback logic in the bootloader to try something else. > >>> + start_enabled: > >>> + Watchdog is started on module insertion. This option can be also > >>> + selected by kernel config (default=kernel config parameter). > >>> + Use only for watchdog drivers which doesn't support this parameter > >>> + by itself. > >> > >> Why ? > > > > There are two drivers with an analogous feature (pnx833x_wdt and > > omap_wdt) and it is important not to enable the watchdog twice. > > > Why ? right, it is a nonsense ... > > > Ok, I can substitute the sentence: " Use only for watchdog drivers > > which doesn't support this parameter itself." with another one, like: > > "If the driver supports this feature by itself, be carefully not to enable > > the watchdog twice". > > > > What do you think? > > > > I am still missing the explanation _why_ it would be important not to enable > a watchdog twice. Why does it matter ? What is the difference ? > > If there is a concern that the start function should not be called on an already > running watchdog, the code could check for that and ensure that > WDOG_HW_RUNNING > is not already set before enabling it. That would probably make sense anyway. > But adding a limitation/restriction like the above, which is not enforceable, > is not a good idea. How would the common user know if a watchdog is already > running (eg because it was started in BIOS/ROMMON) ? Yes, right! I have to check WDOG_HW_RUNNING before starting the watchdog. It is the correct way to manage this feature, in any case and for any wdog driver. > > Thanks, > Guenter Thank you very much Guenter! Regards, Flavio
