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

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Message-ID: <20140828124405.GT24579@lee--X1>
Date:	Thu, 28 Aug 2014 13:44:05 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Beniamino Galvani <b.galvani@...il.com>,
	linux-kernel@...r.kernel.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 Thu, 28 Aug 2014, Guenter Roeck wrote:

> On 08/28/2014 12:19 AM, Lee Jones wrote:
> >On Wed, 27 Aug 2014, Guenter Roeck wrote:
> >>On Wed, Aug 27, 2014 at 12:13:56AM +0200, Beniamino Galvani wrote:
> >>>This adds a driver for the watchdog timer available in Ricoh RN5T618
> >>>PMIC. The device supports a programmable expiration time of 1, 8, 32
> >>>or 128 seconds.
> >>>
> >>>Signed-off-by: Beniamino Galvani <b.galvani@...il.com>
> >>>---
> >>>  drivers/watchdog/Kconfig       |   11 +++
> >>>  drivers/watchdog/Makefile      |    1 +
> >>>  drivers/watchdog/rn5t618_wdt.c |  196 ++++++++++++++++++++++++++++++++++++++++
> >>>  include/linux/mfd/rn5t618.h    |    4 +
> >>>  4 files changed, 212 insertions(+)
> >>>  create mode 100644 drivers/watchdog/rn5t618_wdt.c
> >
> >[...]
> >
> >>>+++ b/drivers/watchdog/rn5t618_wdt.c
> >>>@@ -0,0 +1,196 @@
> >
> >[...]
> >
> >>>+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;
> >
> >This changes the semantics.
> >
> How so ? If ret is set to -EINVAL, the rest of the function won't do anything
> but eventually return -EINVAL. I don't see why returning -EINVAL immediately
> would change that.

Ah, you're right.

I read:

  if (!ret)
    wdt_dev->timeout = rn5t618_wdt_map[i].time;

As:

  if (ret)
    wdt_dev->timeout = rn5t618_wdt_map[i].time;

My bad - withdrawn.

> >>>+	else
> >>
> >>You can drop this else statement.
> >>
> >>>+		ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
> >>>+					 RN5T618_WATCHDOG_WDOGTIM_M,
> >>>+					 rn5t618_wdt_map[i].reg_val);
> >>>+	if (!ret)
> >>>+		wdt_dev->timeout = rn5t618_wdt_map[i].time;
> >
> >... Isn't this important?
> >
> >>>+	return ret;
> >>>+}
> >
> 

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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