linux-kernel - Re: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

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Date:	Tue, 28 Jun 2011 10:35:54 -0700
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	"ashish.jangam@...tcummins.com" <ashish.jangam@...tcummins.com>
CC:	"randy.dunlap@...cle.com" <randy.dunlap@...cle.com>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>,
	"dchen@...semi.com" <dchen@...semi.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>
Subject: Re: [PATCH 6/11] HWMON: DA9052 hwmon driver v1

On Tue, 2011-06-28 at 10:24 -0400, ashishj3 wrote:
> The DA9052 PMIC provides an Analogue to Digital Converter with 10 bits
> resolution and 10 channels.
> 
> This patch montiors the DA9052 PMIC's ADC channels mostly for battery parameters
> like battery temperature, junction temperature, battery current etc.
> 
> Signed-off-by: David Dajun Chen <dchen@...semi.com>
> Signed-off-by: Ashish Jangam <ashish.jangam@...tcummins.com>

[ ... ]

> +static ssize_t da9052_read_vddout(struct device *dev,
> +                                  struct device_attribute *devattr, char *buf)
> +{
> +       struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
> +       int ret, vdd = -1;
> +
> +       mutex_lock(&hwmon->hwmon_lock);
> +
> +       ret = da9052_enable_vddout_channel(hwmon->da9052);
> +       if (ret < 0)
> +               goto hwmon_err;
> +
> +       ret = da9052_reg_read(hwmon->da9052, DA9052_VDD_RES_REG);
> +       if (ret < 0)
> +               pr_err("failed to read VDD_RES_REG\n");
> +       else
> +               vdd = ret;
> +
> +       ret = da9052_disable_vddout_channel(hwmon->da9052);
> +       if (ret < 0)
> +               goto hwmon_err;
> +
> +       if (vdd >= 0) {
> +               mutex_unlock(&hwmon->hwmon_lock);
> +               return sprintf(buf, "%d\n", vdd);
> +       }
> +
> +hwmon_err:
> +       mutex_unlock(&hwmon->hwmon_lock);
> +       return ret;
> +}

This function still produces a bad result if the call to
da9052_reg_read() fails and the call to da9052_disable_vddout_channel()
doesn't. 

I would suggest to replace pr_err() with "goto hwmon_err". If you do
that, you don't need to initialize vdd, you don't need the else case for
its assignment, and you don't need "if (vdd >= 0)" either.

Guenter


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