From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [RFC v4 0/7] extcon: usb-gpio: fixes and improvements Date: Thu, 09 Jun 2016 18:32:42 +0900 Message-ID: <575937BA.1070609@samsung.com> References: <1465393686-16644-1-git-send-email-k.kozlowski@samsung.com> <57592A40.9080608@samsung.com> <57592B4A.4000407@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-reply-to: <57592B4A.4000407-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Krzysztof Kozlowski , MyungJoo Ham , Rob Herring , Mark Rutland , Kukjin Kim , Marek Szyprowski , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: rogerq-l0cyMroinI0@public.gmane.org, Peter Chen , "Ivan T. Ivanov" , balbi-l0cyMroinI0@public.gmane.org, kishon-l0cyMroinI0@public.gmane.org, Bartlomiej Zolnierkiewicz List-Id: devicetree@vger.kernel.org Hi, On 2016=EB=85=84 06=EC=9B=94 09=EC=9D=BC 17:39, Krzysztof Kozlowski wro= te: >=20 > Hi, >=20 >=20 > On 06/09/2016 10:35 AM, Chanwoo Choi wrote: >> Hi, >> >> It is good to support USB_ID and USB_VBUS by extcon. >> >> But, >> there is some issue about adding the new cable type for >> both EXTCON_USB_ID and EXTCON_USB_VBUS >> >> I think that the ID and VBUS state are not cable type >> Instead, ID and VBUS state are the property of USB cable. >> >> So, I'd like to add the following function to support >> the property of each cable as following: >> The client driver can get the state of property by using >> the extcon_get_cable_property_state(). >> >> - int extcon_get_cable_property_state(struct extcon_dev *edev, >> unsigned int id, >> enum extcon_property property); >> - int extcon_set_cable_property_state(struct extcon_dev *edev, >> unsigned int id, >> enum extcon_property property, >> unsigned int state); >> >> For example, >> In extcon-usb-gpio.c, set state of property as follwoing: >> extcon_set_cable_property_state(edev, EXTCON_USB, EXTCON_USB_PROP_I= D, 1); >> extcon_set_cable_property_state(edev, EXTCON_USB, EXTCON_USB_PROP_V= BUS, 1); >> >> >> In the extcon client driver, get state of property as following: >> id_state =3D extcon_get_cable_property_state(edev, EXTCON_USB, EXTC= ON_USB_PROP_ID); >> vbus_state =3D extcon_get_cable_property_state(edev, EXTCON_USB, EX= TCON_USB_PROP_VUBS); >=20 > How one can receive notifications with this API? I think that the extcon don't support the notification only for propert= y. When USB or USB_HOST cable state is changed, the client driver call the extcon_get_cable_property_state() to read the state of propert= y. Namely, the property depend on the specific external connector. >=20 > Last time you wrote, at the end of discussion: > http://thread.gmane.org/gmane.linux.kernel/1923192/focus=3D1923193 >> 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 s= tate, >> 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 metho= d. >> >> 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=09 >> #define EXTCON_USB_VBUS_LOW >> #define EXTCON_USB_VBUS_HIGH >=20 > ... all other participants agreed on that conclusion. So why change o= f > view point now? Unitl now, the extcon framework only handle the state of external conne= ctor(cable). - The state of external connector is either attached or detached. I think that ID and VBUS are not external connector(cable). The ID and VBUS are more appropriate as property than new type of exter= nal connector. Regards, Chanwoo Choi -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html