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

From: "Ivan T. Ivanov" <iivanov@mm-sol.com>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Peter Chen <peter.chen@freescale.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
Date: Thu, 16 Apr 2015 10:13:44 +0300	[thread overview]
Message-ID: <1429168424.26621.1.camel@mm-sol.com> (raw)
In-Reply-To: <552F5E17.5020902@samsung.com>

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.

Ivan