linux-kernel - Re: [PATCH 2/2] extcon: Add the support of EXTCON_CHG_USB when SDP port is attached or detached

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Message-id: <5613BE8B.3030403@samsung.com>
Date:	Tue, 06 Oct 2015 21:28:59 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Roger Quadros <rogerq@...com>, linux-kernel@...r.kernel.org
Cc:	k.kozlowski@...sung.com, ckeepax@...nsource.wolfsonmicro.com,
	gregkh@...uxfoundation.org, ramakrishna.pallala@...el.com,
	patches@...nsource.wolfsonmicro.com, myungjoo.ham@...sung.com
Subject: Re: [PATCH 2/2] extcon: Add the support of EXTCON_CHG_USB when SDP
 port is attached or detached

Roger,

On 2015년 10월 06일 21:22, Roger Quadros wrote:
> Chanwoo,
> 
> On 06/10/15 15:12, Chanwoo Choi wrote:
>> Roger,
>>
>> On 2015년 10월 06일 20:49, Roger Quadros wrote:
>>> Hi,
>>>
>>> On 06/10/15 14:21, Chanwoo Choi wrote:
>>>> The SDP (Standard Downstream Port) is one of various USB Charging ports. The SDP
>>>> supports both the data transmission and the charging through USB connector at
>>>> the same time. So, the EXTCON framework defines two connector type for USB SDP
>>>> connector as following:
>>>> - EXTCON_USB means the USB cable for data transmission.
>>>> - EXTCON_CHG_USB means the USB charger cable for battery charging.
>>>>
>>>> This patch add the support of EXTCON_CHG_USB when USB SDP is attached or
>>>> detached.
>>>
>>> I didn't understand why this change is needed. SDP, EXTCON_USB and EXTCON_CHG_USB
>>> are the same thing. no?
>>
>> As you knew, SDP support both data transmission and charging
>> through one port at the same time. Also, On patch1 of this patch-set,
>> I add the prefix to clarify both attribute and meaning of external connector as following:
>> - EXTCON_CHG_* mean the charger connector.
>>
>> So, there are three possible naming approach for USB SDP.
>>
>> Approach 1.
>> - EXTCON_USB		/* SDP for both data transmission and charging */
>>
>> Approach 2.
>> - EXTCON_USB		/* SDP for data transmission */
>> - EXTCON_CHG_USB	/* SDP for charging */
> 
> This only adds confusion. There is only one cable that will always do both jobs
> so no point in using 2 names for it.

OK. I'll drop it.

> 
>>
>> Approach 3.
>> - EXTCON_CHG_USB	/* SDP for both data transmission and charging */
>>
>> It is not fixed about name. I want to discuss what is proper name for USB SDP.
> 
> I do not have any preference over 1 or 3.

I'll drop this patch. Also, I'll use only EXTCON_USB and delete the EXTCON_CHG_USB
from patch1 on next version.

Thanks,
Chanwoo Choi
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