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. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
