Messages in this thread | | | Date | Thu, 21 May 2015 02:04:40 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH v2 5/7] Watchdog: introduce "pretimeout" into framework |
| |
On 05/21/2015 01:32 AM, fu.wei@linaro.org wrote: > From: Fu Wei <fu.wei@linaro.org> > > Also update Documentation/watchdog/watchdog-kernel-api.txt to > introduce: > (1)the new elements in the watchdog_device and watchdog_ops struct; > (2)the new API "watchdog_init_timeouts". > > Reasons: > (1)kernel already has two watchdog drivers are using "pretimeout": > drivers/char/ipmi/ipmi_watchdog.c > drivers/watchdog/kempld_wdt.c(but the definition is different) > (2)some other dirvers are going to use this: ARM SBSA Generic Watchdog > > Signed-off-by: Fu Wei <fu.wei@linaro.org> > ---
[ ... ]
> +extern int watchdog_init_timeouts(struct watchdog_device *wdd, > + unsigned int pretimeout_parm, > + unsigned int timeout_parm, > + void (*update_limits)(struct watchdog_device *), > + struct device *dev); > > -The watchdog_init_timeout function allows you to initialize the timeout field > -using the module timeout parameter or by retrieving the timeout-sec property from > -the device tree (if the module timeout parameter is invalid). Best practice is > -to set the default timeout value as timeout value in the watchdog_device and > -then use this function to set the user "preferred" timeout value. > +The watchdog_init_timeouts function allows you to initialize the pretimeout and > +timeout fields using the module pretimeout and timeout parameter or by > +retrieving the elements in the timeout-sec property(the first element is for > +timeout, the second one is for pretimeout) from the device tree(if the module > +pretimeout and timeout parameter are invalid). > +Normally, the pretimeout value will affect the limitation of timeout, and it > +is also hardware related. So you can write a function in your driver to update > +the limitation of timeout, according to the pretimeout value. Then pass the > +function pointer by the update_limits parameter. If you driver doesn't > +need this adjustment, just pass NULL to the update_limits parameter.
You've lost me a bit with the update_limits function. watchdog_init_timeouts() is called from the driver. Why should the function have to call back into the driver to update the parameters which are passed from the driver ? Seems to me the driver can do that calculation first, then call watchdog_init_timeouts() with the result. Am I missing something ?
Thanks, Guenter
| |