linux-kernel - Re: [PATCH] iio: adc: fsl-imx25-gcq: fix the right check and simplify code

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Message-ID: <20210802111647.000012ee@Huawei.com>
Date:   Mon, 2 Aug 2021 11:16:47 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     tangbin <tangbin@...s.chinamobile.com>
CC:     Jonathan Cameron <jic23@...nel.org>, <knaack.h@....de>,
        <lars@...afoo.de>, <shawnguo@...nel.org>, <s.hauer@...gutronix.de>,
        <festevam@...il.com>, <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: fsl-imx25-gcq: fix the right check and
 simplify code

On Mon, 2 Aug 2021 10:31:58 +0800
tangbin <tangbin@...s.chinamobile.com> wrote:

> Hi Jonathan:
> 
> On 2021/8/1 0:45, Jonathan Cameron wrote:
> > On Tue, 27 Jul 2021 20:52:09 +0800
> > Tang Bin <tangbin@...s.chinamobile.com> wrote:
> >  
> >> For the function of platform_get_irq(), the example in platform.c is
> >> *		int irq = platform_get_irq(pdev, 0);
> >> *		if (irq < 0)
> >> *			return irq;
> >> So the return value of zero is unnecessary to check. And move it
> >> up to a little bit can simplify the code jump.
> >>
> >> Co-developed-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
> >> Signed-off-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
> >> Signed-off-by: Tang Bin <tangbin@...s.chinamobile.com>  
> > Hi,
> >
> > Logically it is better to keep the irq handling all together, so
> > I would prefer we didn't move it.  
> Got it in this place.
> >
> > Also, platform_get_irq() is documented as never returning 0, so the current
> > code is not incorrect.  As such, this looks like noise unless there is
> > some plan to make use of the 0 return value?  What benefit do we get from
> > this change?  
> 
> Thanks for your reply, I think the benefit of this change maybe just 
> simplify the code.
> 
> Because the return value is never equal to 0, so the check in here is 
> redundant.
> 
> We can make the patch like this:
> 
> >> ---
> >>   drivers/iio/adc/fsl-imx25-gcq.c | 12 ++++--------
> >>   1 file changed, 4 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
> >> index 8cb51cf7a..d28976f21 100644
> >> --- a/drivers/iio/adc/fsl-imx25-gcq.c
> >> +++ b/drivers/iio/adc/fsl-imx25-gcq.c
> >> @@ -320,6 +320,10 @@ static int mx25_gcq_probe(struct platform_device *pdev)
> >>   	if (ret)
> >>   		return ret;
> >>   
> >> +	priv->irq = platform_get_irq(pdev, 0);
> >> +	if (priv->irq < 0)
> >> +		return priv->irq;
> >> +
> >>   	for (i = 0; i != 4; ++i) {
> >>   		if (!priv->vref[i])
> >>   			continue;
> >> @@ -336,14 +340,6 @@ static int mx25_gcq_probe(struct platform_device *pdev)
> >>   		goto err_vref_disable;
> >>   	}
> >>   
> >> -	priv->irq = platform_get_irq(pdev, 0);
> >> -	if (priv->irq <= 0) {
> >> -		ret = priv->irq;
> >> -		if (!ret)
> >> -			ret = -ENXIO;
> >> -		goto err_clk_unprepare;
> >> -	}
> >> -  
> 
> 	priv->irq = platform_get_irq(pdev, 0);
> 	if (priv->irq < 0) {
> 		ret = priv->irq;
> 		goto err_clk_unprepare;
> 	}
> 
>      If you think this is ok, I will send V2 for you. If you think these 
> change is meaningless,

OK, it's a minor tidy up, so lets go with that, or perhaps this is even tidier?
Assuming types of ret and irq are appropriate (I've not checked!)


	ret = platform_get_irq(pdev, 0);
	if (ret)
		goto err_clk_unprepare;

	priv->irq = ret;


> 
> just dropped this.
> 
> Thanks
> 
> Tang Bin
> 
> 
> 
>