linux-kernel - Re: [PATCH] video: backlight: jornada720_lcd.c: Cleaning up variable that is never used

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Date:	Wed, 9 Jul 2014 17:30:50 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Jingoo Han <jg1.han@...sung.com>, Bryan Wu <cooloney@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] video: backlight: jornada720_lcd.c:  Cleaning up
 variable that is never used

On Mon, 07 Jul 2014, Rickard Strandqvist wrote:

> Variable ar assigned a value that is never used.
> I have also removed all the code that thereby serves no purpose,
> and made same change to clarify the similarities in function.
> 
> This was found using a static code analysis program called cppcheck
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
> ---
>  drivers/video/backlight/jornada720_lcd.c |   31 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/video/backlight/jornada720_lcd.c b/drivers/video/backlight/jornada720_lcd.c
> index da3876c..d16abcf 100644
> --- a/drivers/video/backlight/jornada720_lcd.c
> +++ b/drivers/video/backlight/jornada720_lcd.c
> @@ -36,44 +36,41 @@ static int jornada_lcd_get_power(struct lcd_device *ld)
>  
>  static int jornada_lcd_get_contrast(struct lcd_device *ld)
>  {
> -	int ret;
> +	int ret = -ETIMEDOUT;
>  
>  	if (jornada_lcd_get_power(ld) != FB_BLANK_UNBLANK)
>  		return 0;
>  
>  	jornada_ssp_start();
>  
> -	if (jornada_ssp_byte(GETCONTRAST) != TXDUMMY) {
> +	if (jornada_ssp_byte(GETCONTRAST) != TXDUMMY)
>  		dev_err(&ld->dev, "get contrast failed\n");
> -		jornada_ssp_end();
> -		return -ETIMEDOUT;
> -	} else {
> +	else
>  		ret = jornada_ssp_byte(TXDUMMY);
> -		jornada_ssp_end();
> -		return ret;
> -	}
> +
> +	jornada_ssp_end();
> +
> +	return ret;
>  }
>  
>  static int jornada_lcd_set_contrast(struct lcd_device *ld, int value)
>  {
> -	int ret;
> +	int ret = -ETIMEDOUT;
>  
>  	jornada_ssp_start();
>  
>  	/* start by sending our set contrast cmd to mcu */
> -	ret = jornada_ssp_byte(SETCONTRAST);
> -
> +	if (jornada_ssp_byte(SETCONTRAST) != TXDUMMY)
> +		dev_err(&ld->dev, "set contrast failed\n");
>  	/* push the new value */
> -	if (jornada_ssp_byte(value) != TXDUMMY) {
> +	else if (jornada_ssp_byte(value) != TXDUMMY)
>  		dev_err(&ld->dev, "set contrast failed\n");
> -		jornada_ssp_end();
> -		return -ETIMEDOUT;
> -	}
> +	else /* if we get here we can assume everything went well */
> +		ret = 0;
>  
> -	/* if we get here we can assume everything went well */
>  	jornada_ssp_end();
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static int jornada_lcd_set_power(struct lcd_device *ld, int power)

Counter suggestion.

What do you think, I think this looks cleaner:

static int jornada_lcd_get_contrast(struct lcd_device *ld)
{
	int ret;

	if (jornada_lcd_get_power(ld) != FB_BLANK_UNBLANK)
		return 0;

	jornada_ssp_start();

	if (jornada_ssp_byte(GETCONTRAST) == TXDUMMY) {
		ret = jornada_ssp_byte(TXDUMMY);
		goto success;
	}

	dev_err(&ld->dev, "failed to set contrast\n");
	ret = -ETIMEDOUT;

success:
	jornada_ssp_end();
	return ret;
}

static int jornada_lcd_set_contrast(struct lcd_device *ld, int value)
{
	int ret = 0;

	jornada_ssp_start();

	/* start by sending our set contrast cmd to mcu */
	if (jornada_ssp_byte(SETCONTRAST) == TXDUMMY) {
		/* if successful, push the new value */
		if (jornada_ssp_byte(value) == TXDUMMY)
			goto success;
	}

	dev_err(&ld->dev, "failed to set contrast\n");
	ret = -ETIMEDOUT;

success:
	jornada_ssp_end();
	return ret;
}

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