Message-id: <5541DFEA.8060109@samsung.com>
Date: Thu, 30 Apr 2015 16:55:22 +0900
From: Chanwoo Choi <cw00.choi@samsung.com>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106
 Thunderbird/17.0.2
MIME-version: 1.0
To: Roger Quadros <rogerq@ti.com>
Cc: Peter Chen <peter.chen@freescale.com>,
        Robert Baldyga <r.baldyga@samsung.com>,
        "Ivan T. Ivanov" <iivanov@mm-sol.com>, "Balbi, Felipe" <balbi@ti.com>,
        "ABRAHAM, KISHON VIJAY" <kishon@ti.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> <552F724A.1050500@samsung.com>
 <5541DAA0.7030200@ti.com>
In-reply-to: <5541DAA0.7030200@ti.com>
Content-type: text/plain; charset=windows-1252
Content-transfer-encoding: 7bit
DLP-Filter: Pass
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 3037
Lines: 84

On 04/30/2015 04:32 PM, Roger Quadros wrote:
> On 16/04/15 11:26, Chanwoo Choi wrote:
>> 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.
>>
>>
> Chanwoo, Robert,
> 

Hi Roger,

> Do we have an agreement on a common solution then?

Yes.

> IMO the above mentioned 4 notifier events should meet all our USB needs.

I'll support usb notifier chain which includes 4 notifier events.

Thanks,
Chanwoo Choi


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/