linux-kernel - Re: [PATCH 4/6] Watchdog: introdouce "pretimeout" into framework

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Date:	Mon, 18 May 2015 10:23:30 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Fu Wei <fu.wei@...aro.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	Wei Fu <tekkamanninja@...il.com>,
	G Gregory <graeme.gregory@...aro.org>,
	Al Stone <al.stone@...aro.org>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Timur Tabi <timur@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	vgandhi@...eaurora.org, wim@...ana.be,
	Jon Masters <jcm@...hat.com>, Leo Duran <leo.duran@....com>,
	Jon Corbet <corbet@....net>
Subject: Re: [PATCH 4/6] Watchdog: introdouce "pretimeout" into framework

On Tue, May 19, 2015 at 01:19:22AM +0800, Fu Wei wrote:
> Hi Arnd,
> 
> Great thanks for your suggestion :-)
> 
> feedback inline below
> 
> On 15 May 2015 at 22:04, Arnd Bergmann <arnd@...db.de> wrote:
> > On Friday 15 May 2015 19:24:48 fu.wei@...aro.org wrote:
> >> +static void watchdog_check_min_max_pretimeout(struct watchdog_device *wdd)
> >> +{
> >> +       /*
> >> +        * Check that we have valid min and max pretimeout values, if
> >> +        * not reset them both to 0 (=not used or unknown)
> >> +        */
> >> +       if (wdd->min_pretimeout > wdd->max_pretimeout) {
> >> +               pr_info("Invalid min and max pretimeout, resetting to 0!\n");
> >> +               wdd->min_pretimeout = 0;
> >> +               wdd->max_pretimeout = 0;
> >> +       }
> >> +}
> >
> > I would probably just fold this function into the existing
> > watchdog_check_min_max_timeout() and check both normal and pre-timeout
> > there.
> 
> yes, I can do that , and that is good idea
> 
> >
> >> +/**
> >> + * watchdog_init_pretimeout() - initialize the pretimeout field
> >> + * @pretimeout_parm: pretimeout module parameter
> >> + * @dev: Device that stores the timeout-sec property
> >> + *
> >> + * Initialize the pretimeout field of the watchdog_device struct with either
> >> + * the pretimeout module parameter (if it is valid value) or the timeout-sec
> >> + * property (only if it is a valid value and the timeout_parm is out of bounds).
> >> + * If none of them are valid then we keep the old value (which should normally
> >> + * be the default pretimeout value.
> >> + *
> >> + * A zero is returned on success and -EINVAL for failure.
> >> + */
> >> +int watchdog_init_pretimeout(struct watchdog_device *wdd,
> >> +                            unsigned int pretimeout_parm, struct device *dev)
> >> +{
> >> +       int ret = 0;
> >> +       u32 timeouts[2];
> >> +
> >> +       watchdog_check_min_max_pretimeout(wdd);
> >> +
> >> +       /* try to get the timeout module parameter first */
> >> +       if (!watchdog_pretimeout_invalid(wdd, pretimeout_parm) &&
> >> +           pretimeout_parm) {
> >> +               wdd->pretimeout = pretimeout_parm;
> >> +               return ret;
> >> +       }
> >> +       if (pretimeout_parm)
> >> +               ret = -EINVAL;
> >> +
> >> +       /* try to get the timeout_sec property */
> >> +       if (!dev || !dev->of_node)
> >> +               return ret;
> >> +       ret = of_property_read_u32_array(dev->of_node,
> >> +                                        "timeout-sec", timeouts, 2);
> >> +       if (!watchdog_pretimeout_invalid(wdd, timeouts[1]) && timeouts[1])
> >> +               wdd->pretimeout = timeouts[1];
> >> +       else
> >> +               ret = -EINVAL;
> >> +
> >> +       return ret;
> >> +}
> >> +EXPORT_SYMBOL_GPL(watchdog_init_pretimeout);
> >
> > Same here: the function is very similar to the watchdog_init_timeout
> > function, and it reads the same property, so just do both here.
> >
> > The easiest way for that is probably to use of_find_property()
> > and of_prop_next_u32() to read the two numbers.
> 
> integrate watchdog_init_pretimeout and watchdog_init_timeout will be a
> little hard,
> we may need to change this API to :
> 
> watchdog_init_timeouts(struct watchdog_device *wdd, unsigned int timeout_parm,
>                              unsigned int pretimeout_parm, struct device *dev)
> 
> then we need to update all the watchdog drivers which use this API,
> maybe we can do this in a individual patchset, after this pretimeout
> patch is merged.
> 
> Is that OK  ? :-)  any thought?
> 
That is what I would recommend.

Guenter
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