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

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Message-ID: <CADyBb7sMJ=i0XbJWS2dyK4Dc1=gWGGs51soysy7SSyh=7X2M1A@mail.gmail.com>
Date:	Tue, 19 May 2015 01:39:36 +0800
From:	Fu Wei <fu.wei@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
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

Hi Guenter,

np, will do so  :-)

On 19 May 2015 at 01:23, Guenter Roeck <linux@...ck-us.net> wrote:
> 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



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
Room 1512, Regus One Corporate Avenue,Level 15,
One Corporate Avenue,222 Hubin Road,Huangpu District,
Shanghai,China 200021
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