linux-kernel - Re: [PATCH 3/4] watchdog: add driver for Ricoh RN5T618 watchdog

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Message-ID: <20140827221209.GA24987@gmail.com>
Date:	Thu, 28 Aug 2014 00:12:10 +0200
From:	Beniamino Galvani <b.galvani@...il.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Wim Van Sebroeck <wim@...ana.be>,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	Carlo Caione <carlo@...one.org>
Subject: Re: [PATCH 3/4] watchdog: add driver for Ricoh RN5T618 watchdog

On Wed, Aug 27, 2014 at 12:01:35PM -0700, Guenter Roeck wrote:
[...]
> > +#include <linux/device.h>
> > +#include <linux/mfd/rn5t618.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/watchdog.h>
> > +
> > +#define DRIVER_NAME "rn5t618-wdt"
> > +
> > +static bool nowayout = WATCHDOG_NOWAYOUT;
> > +static unsigned int heartbeat = -1;
> 
> I'd be surprised if this doesn't cause a compiler warning.
> Why not just initialize the variable with 0 ?

The idea was to initialize the variable with an invalid value that has
no effect when watchdog_init_timeout() is called during probe, thus
leaving the watchdog timeout to the maximum value.

You are right, the same effect can be achieved in a cleaner way
leaving the variable to zero (by the way, the above assignment doesn't
seem to generate warnings).

> 
> > +
> > +module_param(heartbeat, int, 0);
> > +MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
> > +
> > +module_param(nowayout, bool, 0);
> > +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> > +		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> > +
> > +struct rn5t618_wdt {
> > +	struct watchdog_device wdt_dev;
> > +	struct rn5t618 *rn5t618;
> > +};

[..]

> > +static int rn5t618_wdt_set_timeout(struct watchdog_device *wdt_dev,
> > +				   unsigned int timeout)
> > +{
> > +	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
> > +	int ret, i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(rn5t618_wdt_map); i++) {
> > +		if (rn5t618_wdt_map[i].time + 1 >= timeout)
> > +			break;
> > +	}
> > +
> > +	if (i == ARRAY_SIZE(rn5t618_wdt_map))
> > +		ret = -EINVAL;
> 
> Can you simplify this a bit ? If you use
> 
> 	if (i == ARRAY_SIZE(rn5t618_wdt_map))
> 		return -EINVAL;
> 
> > +	else
> 
> You can drop this else statement.

Will do, thanks.

Beniamino
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