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