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Subject: Re: [PATCH] usb: bdc: Remove duplicate error message in bdc_probe()
To:     Felipe Balbi <balbi@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Florian Fainelli <f.fainelli@gmail.com>
References: <20200927134218.20028-1-tangbin@cmss.chinamobile.com>
 <20200927134550.GA302849@kroah.com>
 <e895f44b-2c53-a883-322b-e3768fdb6733@cmss.chinamobile.com>
 <87sgb29r3g.fsf@kernel.org>
From:   Tang Bin <tangbin@cmss.chinamobile.com>
Message-ID: <02162cfc-cbe3-4747-e518-7f3b3d7a0e7f@cmss.chinamobile.com>
Date:   Mon, 28 Sep 2020 18:55:26 +0800
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Hi Balbi：

在 2020/9/28 17:40, Felipe Balbi 写道:
> Hi,
>
> Tang Bin <tangbin@cmss.chinamobile.com> writes:
>> Hi Greg KH:
>>
>> 在 2020/9/27 21:45, Greg KH 写道:
>>> On Sun, Sep 27, 2020 at 09:42:18PM +0800, Tang Bin wrote:
>>>> In this function, we don't need dev_err() message because
>>>> when something goes wrong, devm_platform_ioremap_resource()
>>>> can print an error message itself, so remove the redundant
>>>> one.
>>>>
>>>> Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
>>>> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
>>>> ---
>>>>    drivers/usb/gadget/udc/bdc/bdc_core.c | 4 +---
>>>>    1 file changed, 1 insertion(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/gadget/udc/bdc/bdc_core.c b/drivers/usb/gadget/udc/bdc/bdc_core.c
>>>> index 02a3a7746..9454f179e 100644
>>>> --- a/drivers/usb/gadget/udc/bdc/bdc_core.c
>>>> +++ b/drivers/usb/gadget/udc/bdc/bdc_core.c
>>>> @@ -508,10 +508,8 @@ static int bdc_probe(struct platform_device *pdev)
>>>>    	bdc->clk = clk;
>>>>    
>>>>    	bdc->regs = devm_platform_ioremap_resource(pdev, 0);
>>>> -	if (IS_ERR(bdc->regs)) {
>>>> -		dev_err(dev, "ioremap error\n");
>>>> +	if (IS_ERR(bdc->regs))
>>>>    		return -ENOMEM;
>>> Why not return the error given to us?
>> Because when get ioremap failed, devm_platform_ioremap_resource() can
>> print error message
>>
>> "dev_err(dev, "ioremap failed for resource %pR\n", res)" in it's called
>> function. So I think this's place's
>>
>> dev_err(dev, "ioremap error\n") is redundant.
> that's not what Greg point you at, though. Greg's concern is valid in
> that instead of passing along the error within bdc->regs, you always
> return -ENOMEM. OTW, your code should read like so:
>
> 	if (IS_ERR(bdc->regs))
>          	return PTR_ERR(bdc->regs);

Thanks for your explain，when I send the patch yesterday, my point is at 
dev_err(), and not aimed at IS_ERR() & PTR_ERR(),

if it's Greg's point, I will change this patch after his reply.


Thank you very much.

Tang Bin