On 14/04/15 13:31, Chanwoo Choi wrote: > 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". I didn't say to add "USB-ID" or "USB-VBUS". solution (a) was to have the following "USB" - attached means ID is high. i.e. Type-B plug attached. "USB-HOST" - attached means ID is low. i.e. Type-A plug attached. "USB-POWER" - attached means USB power is present. i.e. VBUS is alive. This way the definition of USB and USB-HOST remain true to their name and avoid further confusions. VBUS state is got through the "USB-POWER" cable state. > > What is the appropriate method of following two solution? > - Fisrt, use the new cable name "USB-*". I explained this above. > - Second, use the additional API to get the VBUS state. You keep mentioning additional API for VBUS. But I don't see any such API. Can you please suggest what API you are talking about? cheers, -roger > > 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
