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

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Message-ID: <b84ea3e4-5650-d6ac-36f6-98067b286b45@cmss.chinamobile.com>
Date:   Mon, 2 Aug 2021 10:31:58 +0800
From:   tangbin <tangbin@...s.chinamobile.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     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

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,

just dropped this.

Thanks

Tang Bin