Message-id: <552F724A.1050500@samsung.com>
Date: Thu, 16 Apr 2015 17:26:50 +0900
From: Chanwoo Choi <cw00.choi@samsung.com>
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To: Peter Chen <peter.chen@freescale.com>
Cc: "Ivan T. Ivanov" <iivanov@mm-sol.com>, "Balbi, Felipe" <balbi@ti.com>,
        "ABRAHAM, KISHON VIJAY" <kishon@ti.com>, Roger Quadros <rogerq@ti.com>,
        Robert Baldyga <r.baldyga@samsung.com>, myungjoo.ham@samsung.com,
        linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, m.szyprowski@samsung.com
Subject: Re: [PATCH v3 2/4] extcon: usb-gpio: add support for VBUS detection
References: <552CEC97.1050205@samsung.com> <552CEE42.1050907@ti.com>
 <552CFA1E.5070400@samsung.com> <20150415032734.GA29095@shlinux2>
 <552E1862.6090709@ti.com> <552E2EBF.5090906@samsung.com>
 <20150416015922.GB22269@shlinux2> <552F5E17.5020902@samsung.com>
 <1429168424.26621.1.camel@mm-sol.com> <552F6BE3.5080604@samsung.com>
 <20150416080107.GC1709@shlinux2>
In-reply-to: <20150416080107.GC1709@shlinux2>
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On 04/16/2015 05:01 PM, Peter Chen wrote:
> On Thu, Apr 16, 2015 at 04:59:31PM +0900, Chanwoo Choi wrote:
>> On 04/16/2015 04:13 PM, Ivan T. Ivanov wrote:
>>> Hi,
>>>
>>> On Thu, 2015-04-16 at 16:00 +0900, Chanwoo Choi wrote:
>>>> Hi Peter,
>>>>
>>>> On 04/16/2015 10:59 AM, Peter Chen wrote:
>>>>>
>>>
>>>>> Ok, from USB point, external id/vbus value can't decide
>>>>> which role the controller will be, the controller driver
>>>>> will decide role according to many things, eg, user configurations,
>>>>> id/vbus value, OTG HNP, etc.
>>>>>
>>>>> So, from USB controller/phy driver, it doesn't care which cable is
>>>>> inserted, it cares about id/vbus value. Eg, it can get id/vbus value
>>>>> and it will be notified when the id/vbus value has changed.
>>>>
>>>> OK, I change the notifier name and add notifier events as following:
>>>>
>>>> - extcon_{register|unregister}_usb_notifier(struct extcon_dev *edev, struct notifier_block *nb);
>>>> - list of notifier events
>>>>         #define EXTCON_USB_ID_L_VBUS_L0       /* ID low  and VBUS low */
>>>>         #define EXTCON_USB_ID_L_VBUS_H1       /* ID low  and VBUS high */
>>>>         #define EXTCON_USB_ID_H_VBUS_L2       /* ID high and VBUS low */
>>>>         #define EXTCON_USB_ID_H_VBUS_H3       /* ID high and VBUS high */
>>>
>>> I am still confused, why we mix ID and VBUS events into one? 
>>> Those are two lines and they are not necessarily handled by
>>> the same extcon_dev.
>>
>> IMO, if some usb driver check both id and vbus pin at the same time,
>> the usb driver can know the both id and vbus pin state through only one notifier event.
>>
>> Also,
>> If some usb driver want to know the state of id pin except of vbus state,
>> when receiving following events, id pin is low.
>> 	#define EXTCON_USB_ID_L_VBUS_L0
>> 	#define EXTCON_USB_ID_L_VBUS_H1
>> when receiving following events, id pin is high.
>> 	#define EXTCON_USB_ID_H_VBUS_L2
>> 	#define EXTCON_USB_ID_H_VBUS_H3
>> Also, some usb driver would catch the vbus pin state with same method.
>>
>> But, it is just my opinion. We may use following notifier events for each pin.
>> We need to discuss it.
>> 	#define EXTCON_USB_ID_LOW
>> 	#define EXTCON_USB_ID_HIGH	
>> 	#define EXTCON_USB_VBUS_LOW
>> 	#define EXTCON_USB_VBUS_HIGH
>> 	
> 
> I agree with above definition.
> 

OK. I understand.


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