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    SubjectRe: [PATCH v3 2/4] extcon: usb-gpio: add support for VBUS detection
    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




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