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

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Date:	Thu, 16 Apr 2015 15:59:58 +0800
From:	Peter Chen <peter.chen@...escale.com>
To:	"Ivan T. Ivanov" <iivanov@...sol.com>
CC:	Chanwoo Choi <cw00.choi@...sung.com>,
	"Balbi, Felipe" <balbi@...com>,
	"ABRAHAM, KISHON VIJAY" <kishon@...com>,
	Roger Quadros <rogerq@...com>,
	Robert Baldyga <r.baldyga@...sung.com>,
	<myungjoo.ham@...sung.com>, <linux-usb@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<m.szyprowski@...sung.com>
Subject: Re: [PATCH v3 2/4] extcon: usb-gpio: add support for VBUS detection

On Thu, Apr 16, 2015 at 10:13:44AM +0300, 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.

Yes, from consumer side, we only need one element per time, eg vbus
or id.

-- 

Best Regards,
Peter Chen
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