Hi Guenter,
...
> On 4/9/21 2:34 AM, Flavio Suligoi wrote:
> > 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.
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?
>
> >
> > -------------------------------------------------
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > index 0470dc15c085..c2a668d6bbbc 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -47,6 +47,20 @@ config WATCHDOG_NOWAYOUT
> > get killed. If you say Y here, the watchdog cannot be stopped once
> > it has been started.
> >
> > +config WATCHDOG_START_ENABLED
> > + bool "Start watchdog on module insertion"
> > + help
> > + Say Y if you want to start the watchdog at the same time when the
> > + driver is loaded.
> > + This feature is very useful in embedded systems, to avoid cases where
> > + the system could hang before reaching userspace.
> > + This parameter involves the "core" section of the watchdog driver,
> > + in this way it is common for all the watchdog hardware
> > + implementations.
>
> "This parameter applies to all watchdog drivers.". The rest is implementation
> detail and irrelevant here.
Ok
>
> > +
> > + Note: to use only for watchdog drivers which doesn't support this
> > + parameter by itself.
> > +
>
> This comment is quite useless in the Kconfig description. If enabled, it is enabled,
> period.
Ok, I'll remove this comment.
>
> > config WATCHDOG_HANDLE_BOOT_ENABLED
> > bool "Update boot-enabled watchdog until userspace takes over"
> > default y
> > diff --git a/drivers/watchdog/watchdog_core.c
> b/drivers/watchdog/watchdog_core.c
> > index 5df0a22e2cb4..5052ae355219 100644
> > --- a/drivers/watchdog/watchdog_core.c
> > +++ b/drivers/watchdog/watchdog_core.c
> > @@ -43,6 +43,11 @@ static int stop_on_reboot = -1;
> > module_param(stop_on_reboot, int, 0444);
> > MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep
> watching, 1=stop)");
> >
> > +static bool start_enabled =
> IS_ENABLED(CONFIG_WATCHDOG_START_ENABLED);
> > +module_param(start_enabled, bool, 0444);
> > +MODULE_PARM_DESC(start_enabled, "Start watchdog on module insertion
> (default="
> > +
> __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_START_ENABL
> ED)) ")");
> > +
> > /*
> > * Deferred Registration infrastructure.
> > *
> > @@ -224,6 +229,13 @@ static int __watchdog_register_device(struct
> watchdog_device *wdd)
> > * corrupted in a later stage then we expect a kernel panic!
> > */
> >
> > + /* If required, start the watchdog immediately */
> > + if (start_enabled) {
> > + set_bit(WDOG_HW_RUNNING, &wdd->status);
> > + wdd->ops->start(wdd);
> > + pr_info("Watchdog enabled\n");
> > + }
> > +
> > /* Use alias for watchdog id if possible */
> > if (wdd->parent) {
> > ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
> >
Best regards,
Flavio Suligoi
