linux-kernel - Re: [PATCH v3 10/12] hikey960: Support usb functionality of Hikey960

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Message-ID: <c1d606aa-e281-4767-5715-679460f5ce60@huawei.com>
Date:   Mon, 4 Mar 2019 15:31:21 +0800
From:   Chen Yu <chenyu56@...wei.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     <liuyu712@...ilicon.com>, USB <linux-usb@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>,
        Suzhuangluan <suzhuangluan@...ilicon.com>,
        Kongfei <kongfei@...ilicon.com>, <wanghu17@...ilicon.com>,
        <butao@...ilicon.com>, Yao Chen <chenyao11@...wei.com>,
        <fangshengzhou@...ilicon.com>, <lipengcheng8@...wei.com>,
        songxiaowei <songxiaowei@...ilicon.com>,
        xu yiping <xuyiping@...ilicon.com>, <xuyoujun4@...wei.com>,
        <yudongbin@...ilicon.com>, <zangleigang@...ilicon.com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        "Arnd Bergmann" <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Binghui Wang <wangbinghui@...ilicon.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v3 10/12] hikey960: Support usb functionality of Hikey960

Hi,

On 2019/3/4 14:55, Andy Shevchenko wrote:
> On Mon, Mar 4, 2019 at 4:35 AM Chen Yu <chenyu56@...wei.com> wrote:
>> On 2019/3/3 0:01, Andy Shevchenko wrote:
>>> On Sat, Mar 2, 2019 at 11:05 AM Yu Chen <chenyu56@...wei.com> wrote:
> 
>>>> +config HISI_HIKEY_USB
>>>> +       tristate "USB functionality of HiSilicon Hikey Platform"
>>>> +       depends on OF && GPIOLIB
>>>> +       help
>>>> +         If you say yes here you get support for usb functionality of HiSilicon Hikey Platform.
>>>
>>>> +#include <linux/of.h>
>>>
>>> It's hard to see why this have
>>> depends on OF followed by above header inclusion.
>>>
>> This driver depends on devicetree, so I add "depends on OF".
>> But is seems that "#include <linux/of.h>" can be removed after "of_" API
>> have been removed. Thanks for your reminder!
> 
> So, it means that technically there is no such dependency, rather
> administratively.
> 
OK. I will remove the dependent next version.
>>>> +       hisi_hikey_usb->typec_vbus = devm_gpiod_get(dev, "typec-vbus",
>>>> +                       GPIOD_OUT_LOW);
>>>
>>>> +       if (!hisi_hikey_usb->typec_vbus)
>>>> +               return -ENOENT;
>>>
>>> Hmm... Is it possible to get NULL pointer from gpiod_get() at all?
>>>
>>>> +       if (!hisi_hikey_usb->otg_switch)
>>>> +               return -ENOENT;
>>>
>>> Ditto.
>>>
>> I check the comments of devm_gpio_get API, it will not return NULL pointer.
>> But is it more safe to keep the NULL checking? What is your advice?
> 
> Why do we need dead code?
> 
OK.I will remove it.

Thanks
Yu Chen