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Subject: Re: usb: gadget: fsl: Fix a wrong judgment in fsl_udc_probe()
To:     Markus Elfring <Markus.Elfring@web.de>, linux-usb@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
Cc:     Li Yang <leoyang.li@nxp.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Felipe Balbi <balbi@kernel.org>,
        Shengju Zhang <zhangshengju@cmss.chinamobile.com>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel-janitors@vger.kernel.org
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From:   Tang Bin <tangbin@cmss.chinamobile.com>
Message-ID: <a4738b42-b297-766c-56bf-94a91bc82767@cmss.chinamobile.com>
Date:   Fri, 10 Apr 2020 17:15:39 +0800
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Hi Markus:

On 2020/4/10 16:30, Markus Elfring wrote:
>> Hardware experiments show that the negative return value is not just "-EPROBE_DEFER".
> How much will this specific error code influence our understanding
> of the discussed software situation?
>
 From my superficial knowledge, I think we should not  think about it 
too complicated. The return value is just zero or negative, and for 
these negative return value, such as 
"-ENODEV"、"-ENXIO"、"-ENOENT"、“EPROBE_DEFER”，may be the same 
effect。But“-EPROBE_DEFER”has another  importment function: Driver 
requested deferred probing，which is used in cases where the dependency 
resource is not ready during the driver initialization process.
>>>> +        ret = udc_controller->irq ? : -ENODEV;
>>> Will it be clearer to specify values for all cases in such a conditional operator
>>> (instead of leaving one case empty)?
>> I don't know what you mean of "instead of leaving one case empty".
> I suggest to reconsider also the proposed specification “… ? : …”.

What you mean is the way I'm written？

I have provided two ways of patching, both functional can be verified on 
hardware.

Thanks for your patience.

Tang Bin