linux-kernel - Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection at probe

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Date:   Fri, 20 Sep 2019 16:42:04 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Yauhen Kharuzhy <jekhor@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection
 at probe

Hi Andy,

On 19. 9. 18. 오후 4:17, Andy Shevchenko wrote:
> On Wed, Sep 18, 2019 at 2:04 AM Yauhen Kharuzhy <jekhor@...il.com> wrote:
>>
>> On Tue, Sep 17, 2019 at 02:13:22PM +0300, Andy Shevchenko wrote:
>>> On Tue, Sep 17, 2019 at 12:15:36AM +0300, Yauhen Kharuzhy wrote:
>>>> Intel Cherry Trail Whiskey Cove extcon driver connect USB data lines to
>>>> PMIC at driver probing for further charger detection. This causes reset of
>>>> USB data sessions and removing all devices from bus. If system was
>>>> booted from Live CD or USB dongle, this makes system unusable.
>>>>
>>>> Check if USB ID pin is floating and re-route data lines in this case
>>>> only, don't touch otherwise.
>>>
>>>> +   ret = regmap_read(ext->regmap, CHT_WC_PWRSRC_STS, &pwrsrc_sts);
>>>> +   if (ret) {
>>>> +           dev_err(ext->dev, "Error reading pwrsrc status: %d\n", ret);
>>>> +           goto disable_sw_control;
>>>> +   }
>>>> +
>>>> +   id = cht_wc_extcon_get_id(ext, pwrsrc_sts);
>>>
>>> We have second implementation of this. Would it make sense to split to some
>>> helper?
>>
>> Do you mean the combination of regmap_read(...CHT_WC_PWRSRC_STS,
>> &pwrsrc_sts) with cht_wc_extcon_get_id()?
> 
> Yes.
> 
>> In the cht_wc_extcon_pwrsrc_event() function the pwrsrc_sts is checked
>> for other bits also, so separation of PWRSRC_STS read and id calculation
>> to one routine will cause non-clear function calls like as
>> get_powersrc_and_check_id(..., &powersrc_sts, &id) which is not looks
>> better than current code duplication.
> 
> I see. Thanks for answer.
> 
>> Or we need to spend some time for
>> refactoring and testing of cht_wc_extcon_pwrsrc_event() code.
> 
> Perhaps, In any case I'm not objecting of the current approach.
> 

If you think it is OK, could you reply with your tag?
and I'll fix the multi-line comment by myself.


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics