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

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Date:   Mon, 4 Mar 2019 08:55:30 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Chen Yu <chenyu56@...wei.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

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.

> >> +       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?

-- 
With Best Regards,
Andy Shevchenko