From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754521AbbDNKcH (ORCPT ); Tue, 14 Apr 2015 06:32:07 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:40050 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752965AbbDNKb4 (ORCPT ); Tue, 14 Apr 2015 06:31:56 -0400 X-AuditID: cbfee690-f796f6d000005054-7b-552cec98d169 Message-id: <552CEC97.1050205@samsung.com> Date: Tue, 14 Apr 2015 19:31:51 +0900 From: Chanwoo Choi User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-version: 1.0 To: Roger Quadros Cc: Robert Baldyga , myungjoo.ham@samsung.com, linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, "Balbi, Felipe" , "ABRAHAM, KISHON VIJAY" , Peter Chen Subject: Re: [PATCH v3 2/4] extcon: usb-gpio: add support for VBUS detection References: <1427980385-21285-1-git-send-email-r.baldyga@samsung.com> <1427980385-21285-3-git-send-email-r.baldyga@samsung.com> <5525E012.5050207@samsung.com> <552630E4.9030309@samsung.com> <55264148.8070903@samsung.com> <55264534.4020006@samsung.com> <55277910.2070000@samsung.com> <55277FA2.6090700@samsung.com> <55278580.2090809@samsung.com> <55278DD3.3020409@samsung.com> <55279550.1060609@samsung.com> <552CE579.6060702@ti.com> <552CE5C0.3010207@ti.com> In-reply-to: <552CE5C0.3010207@ti.com> Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrNIsWRmVeSWpSXmKPExsWyRsSkWHfGG51Qg87PPBYH79dbzD9yjtXi wtMeNovLu+awWSxa1spssfbIXXaL240r2CyOzf7LZPHg8E52i55HWg5cHv8O9zN59G1Zxehx /MZ2Jo/Pm+QCWKK4bFJSczLLUov07RK4Mvbum8hSMEG14vKBZ6wNjAvkuhg5OSQETCR27T/E BmGLSVy4tx7I5uIQEljKKLF60kJ2mKLT7yezQCQWMUrMeTiPEcJ5wCjx+dsjsCpeAS2Jhs6J TCA2i4CqxK3rG1hBbDag+P4XN8BWiAqESaycfoUFol5Q4sfke2C2iICixL2V68FqmAVWM0ms v5vUxcjBISzgI7HwBivErhvMEveuPWQGiXMKqEk8eOIOUa4uMWneImYIW15i85q3zCD1EgK3 2CXebp4JdY+AxLfJh1hAeiUEZCU2HWCGeExS4uCKGywTGMVmIbloFpKxs5CMXcDIvIpRNLUg uaA4Kb3IRK84Mbe4NC9dLzk/dxMjMA5P/3s2YQfjvQPWhxgFOBiVeHhP+OiECrEmlhVX5h5i NAW6YiKzlGhyPjDa80riDY3NjCxMTUyNjcwtzZTEeV9L/QwWEkhPLEnNTk0tSC2KLyrNSS0+ xMjEwSnVwJi1YO03bmW18B6m5HtRu3STWN5PS3CcalG6TbGAsXm3psEOvY6PgdqpZSrOvVXT n28I2sfs9CRw5bbUDQHWUhY/TkYeS+WKNIvKCvQrlmr53aTn3nkmr2KFXTnDp20Gio+dOibP +bziwNlyQwm/Ks8XRu09J7ktZ3ryTOh9XJ2Q/jpxOvt7JZbijERDLeai4kQARmF6Gr4CAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrKIsWRmVeSWpSXmKPExsVy+t9jAd0Zb3RCDZZ+ZrY4eL/eYv6Rc6wW F572sFlc3jWHzWLRslZmi7VH7rJb3G5cwWZxbPZfJosHh3eyW/Q80nLg8vh3uJ/Jo2/LKkaP 4ze2M3l83iQXwBLVwGiTkZqYklqkkJqXnJ+SmZduq+QdHO8cb2pmYKhraGlhrqSQl5ibaqvk 4hOg65aZA3SPkkJZYk4pUCggsbhYSd8O04TQEDddC5jGCF3fkCC4HiMDNJCwhjFj776JLAUT VCsuH3jG2sC4QK6LkZNDQsBE4vT7ySwQtpjEhXvr2boYuTiEBBYxSsx5OI8RwnnAKPH52yN2 kCpeAS2Jhs6JTCA2i4CqxK3rG1hBbDag+P4XN9hAbFGBMImV06+wQNQLSvyYfA/MFhFQlLi3 cj1YDbPAaiaJ9XeTuhg5OIQFfCQW3mCF2HWDWeLetYfMIHFOATWJB0/cIcrVJSbNW8QMYctL bF7zlnkCo8AsJBtmISmbhaRsASPzKkbR1ILkguKk9FxDveLE3OLSvHS95PzcTYzgKH8mtYNx ZYPFIUYBDkYlHt4TPjqhQqyJZcWVuYcYJTiYlUR45V4BhXhTEiurUovy44tKc1KLDzGaAgNg IrOUaHI+MAHllcQbGpuYGVkamRtaGBmbK4nzztGVCxUSSE8sSc1OTS1ILYLpY+LglGpgXFgY dnbjdqZfNv0LVrhZcCzZdDu4Ov2U24d2nv83PwebPpl34Njt2Zevsrnz36ndfD3oTpTP5X9H N9z4MvPByatyf2bHTH0qF3zS8VVHfPFG+x+TZk68Mef5tiCmuPn/u9Z4LW598eqER3JXxq8P hzgU9Rq1eVbuiMw6dWa+zEzJe/+r41P3O+opsRRnJBpqMRcVJwIAUgJzEAgDAAA= DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/14/2015 07:02 PM, Roger Quadros wrote: > Fixed Kishon's id. > > On 14/04/15 13:01, Roger Quadros wrote: >> On 10/04/15 12:18, Chanwoo Choi wrote: >>> On 04/10/2015 05:46 PM, Robert Baldyga wrote: >>>> On 04/10/2015 10:10 AM, Chanwoo Choi wrote: >>>>> On 04/10/2015 04:45 PM, Robert Baldyga wrote: >>>>>> On 04/10/2015 09:17 AM, Chanwoo Choi wrote: >>>>>>> Hi Robert, >>>>>>> >>>>>>> On 04/09/2015 06:24 PM, Robert Baldyga wrote: >>>>>>>> Hi Chanwoo, >>>>>>>> >>>>>>>> On 04/09/2015 11:07 AM, Chanwoo Choi wrote: >>>>>>>>> Hi Robert, >>>>>>>>> >>>>>>>>> On 04/09/2015 04:57 PM, Robert Baldyga wrote: >>>>>>>>>> Hi Chanwoo, >>>>>>>>>> >>>>>>>>>> On 04/09/2015 04:12 AM, Chanwoo Choi wrote: >>>>>>>>>>> Hi Robert, >>>>>>>>>>> >>>>>>>>> >>>>>>>>> [snip] >>>>>>>>> >>>>>>>>>>> But, I have one question about case[3] >>>>>>>>>>> >>>>>>>>>>> If id is low and vbus is high, this patch will update the state of both USB and USB-HOST cable as attached state. >>>>>>>>>>> Is it possible that two different cables (both USB and USB-HOST) are connected to one port simultaneously? >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> It's because state of single USB cable connection cannot be completely >>>>>>>>>> described using single extcon cable. USB cable state has two bits (VBUS >>>>>>>>>> and ID), so we need to use two cables for single cable connection. We >>>>>>>>>> use following convention: >>>>>>>>>> cable "USB" = VBUS >>>>>>>>>> cable "USB-HOST" = !ID. >>>>>>>>> >>>>>>>>> I think that extcon provider driver have to update the only one cable state >>>>>>>>> of either USB or USB-HOST because USB and USB-HOST feature can not be used >>>>>>>>> at the same time through one h/w port. >>>>>>>>> >>>>>>>>> If extcon-usb-gpio.c update two connected event of both USB and USB-HOST cable >>>>>>>>> at the same time, the extcon consumer driver can not decide what handle either USB or USB-HOST. >>>>>>>>> >>>>>>>> >>>>>>>> It can. USB OTG allows for that. Moreover device can be host even if >>>>>>>> ID=1 (so detected cable type is USB device), or peripheral when ID=0 (so >>>>>>>> detected cable type is USB host). Devices would need to have complete >>>>>>>> information about USB cable connection, because OTG state machine needs >>>>>>> >>>>>>> As I knew, USB OTG port don't send the attached cable of both USB and USB-HOST >>>>>>> at the same time. The case3 in your patch update two cable state about one h/w port. >>>>>>> >>>>>> >>>>>> It's because simple "USB" or "USB-HOST" means nothing for USB OTG >>>>>> machine. It needs to know exact VBUS and ID states, which cannot be >>>>>> concluded basing on cable type only. That's why I have used "USB-HOST" >>>>>> name together with "USB" to pass additional information about USB cable >>>>>> connection. >>>>> >>>>> I think this method is not proper to support this case. >>>>> It may cause the confusion about other case using USB/USB-HOST cable state >>>>> except of you commented case. >>>> >>>> That's why I finally proposed to use "USB-ID" and "USB-VBUS" in parallel >>>> with old names. It seems to be simpler solution than adding new >>>> mechanism notifying about VBUS and ID states changes. >>> >>> >>> As I commented on previous reply, I don't agree to use 'USB-ID' and 'USB-VBUS'. >>> If we add new strange 'USB-ID' and 'USB-VBUS' name, we would add non-general cable >>> name continuoulsy. >>> >>> I think that extcon core provide the helper API to get the value of VBUS. >>> But I need to consider it. >> >> Now it is starting to look like existing extcon states are not suitable for USB/PHY drivers to deliver >> VBUS and ID information reliably. >> This is because based on your comments the "USB" and "USB-HOST" states look like some fuzzy states >> and have no direct correspondence with "VBUS" and "ID". The fact that they can't become >> attached simultaneously makes me conclude that "USB" and "USB-HOST" cable states are really >> capturing only the ID pin state. >> >> I can suggest the following options >> a) let "USB" and "USB-HOST" only indicate ID pin status. Add a new cable state for "VBUS" notification. >> Maybe call it "USB-POWER" or something. We must discuss it before using the new cable name such as "USB-POWER", "USB-ID" and "USB-VBUS". What is the appropriate method of following two solution? - Fisrt, use the new cable name "USB-*". - Second, use the additional API to get the VBUS state. Cheers, Chanwoo Choi >> >> NOTE: "USB-POWER" can become attached simultaneously with "USB" or "USB-HOST". But "USB-POWER" is now really >> a different cable like "Fast-Charger" or "Slow-Charger". >> >> b) stop using extcon framework for USB VBUS and ID notification.