From mboxrd@z Thu Jan 1 00:00:00 1970 From: cw00.choi@samsung.com (Chanwoo Choi) Date: Thu, 09 Jun 2016 18:32:42 +0900 Subject: [RFC v4 0/7] extcon: usb-gpio: fixes and improvements In-Reply-To: <57592B4A.4000407@samsung.com> References: <1465393686-16644-1-git-send-email-k.kozlowski@samsung.com> <57592A40.9080608@samsung.com> <57592B4A.4000407@samsung.com> Message-ID: <575937BA.1070609@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 2016? 06? 09? 17:39, Krzysztof Kozlowski wrote: > > Hi, > > > 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_ID, 1); >> extcon_set_cable_property_state(edev, EXTCON_USB, EXTCON_USB_PROP_VBUS, 1); >> >> >> In the extcon client driver, get state of property as following: >> id_state = extcon_get_cable_property_state(edev, EXTCON_USB, EXTCON_USB_PROP_ID); >> vbus_state = extcon_get_cable_property_state(edev, EXTCON_USB, EXTCON_USB_PROP_VUBS); > > How one can receive notifications with this API? I think that the extcon don't support the notification only for property. When USB or USB_HOST cable state is changed, the client driver call the extcon_get_cable_property_state() to read the state of property. Namely, the property depend on the specific external connector. > > Last time you wrote, at the end of discussion: > http://thread.gmane.org/gmane.linux.kernel/1923192/focus=1923193 >> 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 > > ... all other participants agreed on that conclusion. So why change of > view point now? Unitl now, the extcon framework only handle the state of external connector(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 external connector. Regards, Chanwoo Choi