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

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Date:   Mon, 4 Mar 2019 10:35:13 +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 Andy,

On 2019/3/3 0:01, Andy Shevchenko wrote:
> On Sat, Mar 2, 2019 at 11:05 AM Yu Chen <chenyu56@...wei.com> wrote:
>>
>> This driver handles usb hub power on and typeC port event of HiKey960 board:
>> 1)DP&DM switching between usb hub and typeC port base on typeC port
>> state
>> 2)Control power of usb hub on Hikey960
>> 3)Control vbus of typeC port
> 
>> +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!
>> +       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?
>> +       /* hub-vdd33-en is optional */
>> +       hisi_hikey_usb->hub_vbus = devm_gpiod_get(dev, "hub-vdd33-en",
>> +                       GPIOD_OUT_HIGH);
> 
> devm_gpio_get_optional() if it's indeed optional.
> 
OK.Thanks!
>> +       hisi_hikey_usb->role_sw = usb_role_switch_get(dev);
>> +       if (!hisi_hikey_usb->role_sw)
>> +               return -EPROBE_DEFER;
> 
>> +       else if (IS_ERR(hisi_hikey_usb->role_sw))
> 
> Redundant 'else'
> 
OK.
>> +               return PTR_ERR(hisi_hikey_usb->role_sw);
> 
>> +static const struct of_device_id id_table_hisi_hikey_usb[] = {
>> +       {.compatible = "hisilicon,gpio_hubv1"},
>> +       {.compatible = "hisilicon,hikey960_usb"},
>> +       {}
>> +};
> 
> MODULE_DEVICE_TABLE()?
> 
OK.

Thanks
Yu Chen