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. > > 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. > > cheers, > -roger > >> >>> >>>> >>>>> >>>>>> I don't agree. >>>>>> >>>>>>> that. As I wrote, current USB cable names are misleading. It would be >>>>>>> better to have "USB-VBUS" and "USB-ID". >>>>>> >>>>>> It is strange cable name. I prefer to use only 'USB' cable name. >>>>>> But, we could support the other method to get the state of whether USB-VBUS or USB-ID >>>>>> by using helper API or others. >>>>>> >>>>> >>>>> Ok, so do you have any idea how to do it? Do we want to supply >>>>> additional API for notifying about VBUS and ID changes? >>>> >>>> No, we need to consider more standard solution to support this case. >>>> >>> >>> Thanks, >>> Robert Baldyga >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> Please read the FAQ at http://www.tux.org/lkml/ >>> >> > -- 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
