linux-kernel - Re: [PATCH] usb: fotg210-hcd: Fix an error message

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Message-ID: <75002e1a-bca7-8726-de2e-56905f255693@wanadoo.fr>
Date:   Fri, 7 May 2021 09:06:57 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     gregkh@...uxfoundation.org, shubhankarvk@...il.com,
        lee.jones@...aro.org, gustavoars@...nel.org, vulab@...as.ac.cn,
        john453@...aday-tech.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] usb: fotg210-hcd: Fix an error message

Le 07/05/2021 à 04:20, Chunfeng Yun a écrit :
> On Thu, 2021-05-06 at 22:39 +0200, Christophe JAILLET wrote:
>> 'retval' is known to be -ENODEV here.
>> This is a hard-coded default error code which is not useful in the error
>> message. Moreover, another error message is printed at the end of the
>> error handling path. The corresponding error code (-ENOMEM) is more
>> informative.
>>
>> So remove simplify the first error message.
>>
>> While at it, also remove the useless initialization of 'retval'.
>>
>> Fixes: 7d50195f6c50 ("usb: host: Faraday fotg210-hcd driver")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>>   drivers/usb/host/fotg210-hcd.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/host/fotg210-hcd.c b/drivers/usb/host/fotg210-hcd.c
>> index 6cac642520fc..9c2eda0918e1 100644
>> --- a/drivers/usb/host/fotg210-hcd.c
>> +++ b/drivers/usb/host/fotg210-hcd.c
>> @@ -5568,7 +5568,7 @@ static int fotg210_hcd_probe(struct platform_device *pdev)
>>   	struct usb_hcd *hcd;
>>   	struct resource *res;
>>   	int irq;
>> -	int retval = -ENODEV;
>> +	int retval;
>>   	struct fotg210_hcd *fotg210;
>>   
>>   	if (usb_disabled())
>> @@ -5588,7 +5588,7 @@ static int fotg210_hcd_probe(struct platform_device *pdev)
>>   	hcd = usb_create_hcd(&fotg210_fotg210_hc_driver, dev,
>>   			dev_name(dev));
>>   	if (!hcd) {
>> -		dev_err(dev, "failed to create hcd with err %d\n", retval);
>> +		dev_err(dev, "failed to create hcd\n");
>>   		retval = -ENOMEM;
> How about moving this line before dev_err()? then could keep error log
> unchanged.
> 

Mostly a matter of taste.
I don't think it add any useful information (this is not something 
coming from a call chain or that can have different values, it is just a 
hard-coded constant) and the line after we will already have:
	dev_err(dev, "init %s fail, %d\n", dev_name(dev), retval);
where retval = -ENOMEM

So the -ENOMEM error code is already reported.

Moreover, having error code reported or not is already not consistent in 
the function. For example "failed to enable PCLK\n" where 'retval' could 
be reported as well.



BTW, is it useful to have 'dev_name(dev)' in a dev_err?

CJ

>>   		goto fail_create_hcd;
>>   	}
>